There is a bit of confusion out there because R# 3.0.2 doesn't immediately support code analysis and intellisense for the new C# 3.0 features like LINQ queries, etc.  What I've heard is that in Q12008, we'll have a R# that will support all the new stuff.  While it's a shame that it's not ready to go immediately (because VS 2008 RTM is available as of this week), we can still us R# 3.0.2 with VS 2008 to get most of the value and ease of use we've come to expect from a productivity add-in.  Here are the steps:

First, the big problem is that when we start using new features in VS 2008, R# doesn't cooperate because it doesn't know about the new syntax that's now available.  The on-the-fly code analysis goes haywire as depicted in the screenshot below:

Not only does the code analysis not work properly, but the R# intellisense we get doesn't show the proper options with extension methods.  We'll go to Resharper>Options and change two settings.  First, let's turn off R# code analysis:

Next, we'll tell R# to let VS give us intellisense since VS knows about the full options:

Now, if we look back at the code, all the red goes away, and our intellisense window has full support, like the "where" keyword in the LINQ query below:

With these two changes, we get rid of the immediate annoyances, but we can continue to leverage all the other great features R# gives us like file/type navigation, NANT/NUNIT support, etc.

If you have any more tips that would be helpful during the interim for using R# 3.0.2 with VS 2008 until R#4 comes out, please post a comment.