Resharper 4.0 with CS 3.0 support has just got available. Lots of features are (will be?) added to this version with which you can work on VisualStudio .NET 2008. Some of them are:

  • Extension Methods support.
  • Object and Collection initializers support.
  • Automatic property support.
  • Partial lambda support.

The team in JetBrains are still working on full Lambda and LINQ support so it will take some time to mature.

Additional information can be found here which you need to read before you decide to use it or not.