Interesting undertaking to develop a new RFO Style Guide (RFOSG), to enhance the possibility of sharing content – over at the Revit Forum.

Here is the latest PDF version:
Revit Style Guide v0.2 pdf

And here is a sample of some of the contents:
Naming Conventions     4
Separators and Case     4
System Families     4
Loadable Families     5
Materials     7
Fill Patterns (Surface)     8
Fill Patterns (Cut)     8
Line Patterns     9
Line Styles     9
Line Weights     9
Text Styles     9

It is also in a nice ‘open’ format:

This document is developed and released under the Creative
Commons with Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0)
(Commonly referred to as “CopyLeft”)
You are free:
to Share – to copy, distribute and transmit the work
to Remix – to adapt the work 

Revit Style Guide – First Draft