I need to post on the assembly version number for Whidbey again, for two reasons: (A) I never posted what it actually was, and (B) I posted some inaccurate data that I'd like to correct.

(A) is easy. The assembly version number for Beta 2 and RTM is: 2.0.0.0. This may seem to make sense for a version number, however for Everett it was 1.0.5000.0 -- not sure why that was chosen. 

(B) is slightly more complicated. I said in an earlier post that apps built on top of Whidbey Beta 1 (or earlier) would need to be recompiled. That is not true. They will work fine on Whidbey RTM without re-compilation. What will not work is Whidbey RTM apps running on the Whidbey beta 1 runtime -- which is presumably not a scenario for anyone.

(B) is true due to framework unification, which only applies to .NET Framework assemblies (i.e. System.Web.dll). The assembly binder basically does a quick test to determine if the version of a framework assembly is higher or lower than the one that ships with a given runtime -- meaning the runtime currently being run in the process. If it is higher, the load is rejected; if it is lower or equal, the referenced version number is ignored and the version that shipped with that runtime is loaded instead. We go through this algorithm to prevent Everett System.Web.dll running on Whidbey with Whidbey System.dll. Those configurations are not supported, so we prevent them from occuring.