The only new .Net 3.5 technology we're actually using so far is LINQ. We've been using anonymous filter methods and other quasi-LINQ constructs to do collection manipulation for a while in 2.0, so it was a low hanging fruit, and we embraced it right away. Other than that, as a BPM guy, I personally expected so much more from WWF that I don't see me using it for the foreseeable future. The other ones, we're evaluating and doing some prototyping, and if them prove themselves worth it, why not?