It is version 47 in RC and it may very well change when R2 gets RTM. You can check the objectVersion attribute of your current forest on the Schema Naming Context (NC) via ADSIedit.msc.

Here are some older Schema versions.

13=Win2k
30=2003
31=2003R2
44=2008

Here is more detail of schema changes in Windows Server 2008 R2 RC.

http://technet.microsoft.com/en-us/library/dd378828(WS.10).aspx