I was just reading Jeremy Miller's recent blog where he states that he is waiting for ReSharper 4.0 before he starts using VS 2008.

As most of us Resharper enthusiasts know current version 3.1 does not work well with Visaul Studio 2008.   To be more specific, some of the C# 3.0 features like Extension methods and Lambda Expressions "confuse" Resharper and it ends up reporting that as a syntax error, where it is just a new language feature. 

From the image above you can see the effects of that.  However there is a ReSharper shortcut key which allows us to turn of ReSharper validation only for current file being edited.  If you press "Ctr+8" you will turn off/on ReSharper validation on file being currently edited.  Since I do not have Labmda expresions in each code file in my project this feature allows me to still use ReSharper for VS 2008 projects.

Bellow is the screen shot of the same code file after pressing Ctr+8: