Cross Forest Group security Scope

Hello,

I need a confirmation about this documentation on windows 2008R2 server:

Group scope

http://technet.microsoft.com/en-us/library/cc755692(WS.10).aspx

I can't find a related document in windows 2008R2 server.

I need an official answer to give to my customer and an article on W2003 server is not enough.

Could someone help me?

Thanks in advance.

Hervé.