Note: If you install the non-Subscription Update Release onto an R2 Revit, you will probably find that the nice extra things like Site Designer disappear. If this happens to you, reinstall R2 from the Subscription page and your new features should come back. The Autodesk_Revit_2015_R2_UR5.sfx.exe should hopefully not ‘break’ your R2 install.
More at:
http://knowledge.autodesk.com/support/revit-products/downloads/caas/downloads/content/autodesk-revit-2015-update-release-5.html

Direct link:
http://download.autodesk.com/SWDLDDLM/Updates/RVT/UR5/Autodesk_Revit_2015_R2_UR5.sfx.exe

Readme:
http://download.autodesk.com/SWDLDDLM/Updates/RVT/UR5/Autodesk_Revit_2015_R2_UR5_Readme.htm

Enhancement List:
http://revit.downloads.autodesk.com/download/2015RVT_RTM/UR5/Enhancements_List_RVT_2015_UR5_forR2.pdf

EDIT: More links from Revit Clinic:
Direct links:
Revit 2015 UR5
Revit Arch 2015 UR5
Revit MEP 2015 UR5
Revit Struct 2015 UR5
Revit LT 2015 UR5
Installation Readme files and Enhancements Documentation are available on each product page.

UR5 enhancements:
Improvements made in Update Release 5 build (20141119_0715):
 

Autodesk® Revit® Architecture 2015 Updates
Improves resolving of the Revit Server saved paths.*
Corrects the behavior of placing families in a project when the family type selector is expanded.
Improves stability when loading families that contain data created by add-ins.
Improves stability when ungroup a group.
Improved stability when filter a schedule.
Improved stability when opening projects with bad dimensions.
Improves stability when making edits in the Sun Settings dialog.
Improves stability when deleting parts while modifying division.
Improves stability when canceling new label creation in family environment.
Improves stability when editing materials in families in a workshared environment.
Improves stability when clicking the Macro Manager tool in the Family Editor.
Improves stability when multiple users load families and undo their actions in a workshared file.
Improves stability when two users loaded families of the same name.
Corrects an issue with ceiling-hosted lights that caused the lights to be deleted when the ceiling was moved or copied.*
Corrected an issue related to placement of face-based families on certain part elements.*

Autodesk® Revit® MEP 2015 Updates
Improves stability when editing a conduit temporary dimension in an elevation view.

Autodesk® Revit® Structure 2015 Updates
Improves stability when exporting multi-rebar annotation into DWG format.*
Corrects an issue with incorrect warning and error messages for groups in design options with a group containing structural framing elements or columns.*
Fixed an issue with the generation of the analytical surface for a vertical floor and slab.

Autodesk® Revit® API 2015 Updates
Allows the ability to offset the end of a wire when it is connected to other elements.

Here you go:

Revit 2014 Update Release 3

Revit 2014 UR3 (32-bit) (exe – 68327Kb)
Revit 2014 UR3 (64-bit) (exe – 106583Kb)

Revit Architecture 2014 Update Release 3

Revit Architecture 2014 UR3 (32-bit) (exe – 68327Kb)
Revit Architecture 2014 UR3 (64-bit) (exe – 106583Kb)

Revit Structure 2014 Update Release 3

Revit Structure 2014 UR3 (32-bit) (exe – 68327Kb)
Revit Structure 2014 UR3 (64-bit) (exe – 106583Kb)

Revit MEP 2014 Update Release 3

Revit MEP 2014 UR3 (32-bit) (exe – 68327Kb)
Revit MEP 2014 UR3 (64-bit) (exe – 106583Kb)

Revit LT 2014 Update Release 3

Revit LT 2014 UR3 (32-bit) (exe – 68327Kb)
Revit LT 2014 UR3 (64-bit) (exe – 106583Kb)

Installation Readme files and Enhancements Documentation are available on each product page.

From:
http://revitclinic.typepad.com/my_weblog/service-packs/

Heads-up
https://twitter.com/TroyGates/status/491279341150429184

Straight copy from Revit Clinic:

Update Release 3 for Revit 2015 has been released to the App Manager. However, if the App Manager is not finding the update, you can download them directly from the links below:
Revit 2015
Revit Architecture 2015
Revit MEP 2015
Revit Structure 2015
Revit LT 2015 (64-bit)
Revit LT 2015 (32-bit)

Original post:
Revit 2015 – Update Release 3 – The Revit Clinic

Check your Autodesk Application Manager:

Revit 2015 will now read “Update Release 2” in the About box:

Readme:
http://download.autodesk.com/SWDLDDLM/Updates/2015/RVT/Revit_2015_Update_2_Readme.htm

Direct download link for Revit 2015 Update 2:
http://download.autodesk.com/SWDLDDLM/Updates/2015/RVT/Autodesk_Revit_2015-x64_Update2.exe

Also see:
http://knowledge.autodesk.com/support/revit-products/downloads#?ADSKContentGroup-local=Downloads&ADSKProductLine=Revit%20Products&ADSKReleaseYear=2015&sort=score&page=1

Depending which Revit 2015 installer you used, you may need to install this. More info at:
http://download.autodesk.com/SWDLDDLM/Updates/2015/REVIT/Revit_2015_Update_1_Readme.htm

Revit 2015 Update Release 1 Enhancements documentation:
http://revit.downloads.autodesk.com/download/2015RVT_RTM/UR1/Enhancements_List_RVT_2015_UR1.pdf

Autodesk® Revit® Platform 2015 Enhancements

  • Improves data integrity when editing nested families.
  • Improves stability when editing nested families. 
  • Improves stability when editing when expanding schedule columns.
  • Improves upgrade of projects which contain rebar elements.
  • Removes format constraints for assembly codes.
  • Improves data collection when Customer Involvement Program is enabled

Just remember – the application manager will by default store downloaded packages in:
C:UsersUSERNAMEDocumentsAutodesk Application Manager

Is available, if you use the Communications Center in your Revit 2014 product.

Direct Download for Revit 2014 Update Release 1:
http://updatesdl.autodesk.com/updates/files/rvt2014ur11.exe

Readme

The Live Updater from in-program uses mshta.exe to download and execute the file.

On Windows 7 64 bit, you might be able to prompt the download page by opening:
file:///C:/Program%20Files/Autodesk/Revit%202014/WebServices/WSLiveUpdate.htm

Also, after using Comm Center, you will find a HTA in this folder that you can run:
C:UsersUSERNAMEAppDataLocalAutodesk, IncAutodesk Revit20130308_1515(x64)

Heads-up via tweet from Steve Stafford:

Forum:

Just in case you missed it, Update Release 3 is available for all 4 Revit flavours (links below).

Key fixes (as per documentation):

  • Improves stability when using Hardware Acceleration, Graphics Mode.   
  • Improves stability when opening projects which utilize Extensible Storage.
  • Improves visual fidelity between canvas and printed output.   
  • Improves visual fidelity of hidden lines, MEP pipe centerlines and haloed gaps when not using Hardware Acceleration, Graphics Mode.   
  • Improves Structural family data integrity during upgrade of project.
  • Improves data integrity when canceling Save As operation.
  • Improves interaction between Revit Server 2013 and Riverbed compression.
  • Enables users to browse Revit Server Networks when a bound workstation cannot contact the Domain Controller.  

 Dave Baldacchino informs us that this update includes the Hotfix that fixes some nasty non-WYSIWYG bugs (when printing in vector):
Anyway, I also checked that the recent Update 3 (for OneBox)incorporates this hotfix as well, so just skip it altogether and install Update 3 as fast as you can. There are separate downloads for the stand-alone packages.
via
http://do-u-revit.blogspot.com.au/2013/06/what-you-see-is-not-what-you-get.html

Link for RVT (Onebox):
http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=21891257&linkID=21208796

Link for RAC:
http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=21890399&linkID=9273944

Link for MEP:
http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=21891036&linkID=21208796

Link for RST:
http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=21890545&linkID=21208796

I guess the fact that we are receiving a significant update to 2013 after getting 2014 will be a further warning to some users to delay the 2014 rollout…