I'm a little late to the party on this one, but I just watched Anders Hejlsberg's announcement (... from 2010) on it and must say that I am very impressed.

async and await will make asynchronous development an absolute breeze. Having not done much with it myself, I can't really give any tips, pointers, advice or musings, but here is the video from PDC 10 announcing it, and Eric Lippert's blog posts running through the details.

One question I had was about how asynchronism works with only one thread, you can find a bit of a run through it here.