Well, sadly, we don't have it yet.
You can still access the 2010 version here and the 2009 version here.
I don't know about you, but I would love an updated Families Guide for 2011.
Some of the information in this guide is invaluable. I have actually requested that Autodesk put together a comprehensive guide relating to Revit Categories (SR# 1-9298685321 - The help file does not describe the unique properties of each Category).
Here is an example of the information in the 2010 guide (this is copyright to Autodesk obviously):