Finally we have announced C# Edit and Continue, the 2nd most requested feature in all of VS (according to the Ladybug tool). The whole team across all the disciplines really pulled together to get it done.
As a point of history you can read my original blog on the subject of why we were not doing it. Sometimes I cannot reveal the full story of things at the time, and this was one of those times. Sorry.
It was in reasonable shape for beta 1, but it was disabled in that build right before we shipped it. At least you can try it yourselves now. Enjoy!