Why do Silverlight 4 Assemblys still have the version 2.0.5.0?

Question

Why do Silverlight 4 Assemblys still have the version 2.0.5.0 in Visual Studios Object Browser?

Answer 1

Because it needs to reference the System.Core 2.0.5.0

Answer 2

Well I can't claim to know the exact reason for this, you would need someone from the SL team to state the reason categorically and I haven't seen any blogs from them doing that.

However I strongly suspect this is related to the fact that there is still only one Silverlight plugin, that is to say when a user installs the Silverlight 4 plugin it replaces the existing one. The Silverlight 4 plugin will run not only Silverlight 4 apps but also Silverlight 3 and 2 apps. As a consequence Silverlight 2 apps will be looking for 2.0.5.0 libraries and that certain issues are avoided if the later versions simply use the same version number.

Of course I could be way off and hope that if I am an MS geezer come and shoot this down, in the process of which giving us the real answer.