Update: now try this method

Revit Architecture 2012

Revit Structure 2012

Revit MEP 2012

I recommended using Firefox with Downthemall to download these files. Finally, be sure to confirm the checksums / hashes before beginning the install.
EDIT:  Some people were having problems with these links.  However, this should no longer be a problem.
If you are interested in Student version links, go to this page.

Revit Architecture 2012

Revit Structure 2012

Revit MEP 2012

I recommended using Firefox with Downthemall to download these files. Finally, be sure to confirm the checksums / hashes before beginning the install.
EDIT:  Some people were having problems with these links.  However, this should no longer be a problem.
If you are interested in Student version links, go to this page.

Here it is:

http://revit.downloads.autodesk.com/download/2012RAC_RTM/Autodesk_Revit_Architecture_2012_English_Win_32-64bit.exe

Here is the readme:
http://revit.downloads.autodesk.com/download/2012RAC_RTM/Docs/Revit%20Architecture%20Readme.htm

System requirements:
http://usa.autodesk.com/revit-architecture/system-requirements/

Remember where you heard it first!  And feel free to subscribe.