PaulV discusses language divergence.  It looks like VB.NET Whidbey will get back the famous edit and continue (C# will likely have the same feature).  There are also undertones in Paul's post that seem to indicate there will be more divergence between VB.NET and C# if it is good for developers.  So if you are looking to know the two premiere .NET languages, it would be wise to learn VB.NET now, when it is so similar to C# (or vice versa).  This way, when (and if) the languages do diverge, it will simply be a matter of learning the new features in both and the new differences between the two.