We actually have the LINQ IntelliPrompt on 'w' working for C# here but it's still in development due to some timing issues we need to resolve. Since our LINQ resolver is currently tied to the AST, if the AST is out of date (like in large documents) the IntelliPrompt results don't work as well. We need to try and improve that yet.
We also need to implement the LINQ resolver functionality for VB yet, which we haven't started yet.
I don't have a date at this time. The highest priority at the moment is getting 2012.1 done and out (getting close), and LINQ support may be something we work on more as a maintenance release feature for that.