The other day, Don Box announced the availability of the Indigo Community Technology Preview docs. Now the builds are available on MSDN! (I suppose only to MSDN subscribers) I've been looking forward to this for a while now. I'm definitely going to be playing with it this evening. I suppose I'll have to give up some Halo time.
For those who don't know what Indigo is, it's the unified programming model for building message-based, service-oriented applications. It abstracts all the trickiness from you. I won't get too much into it because the documentation does a fairly impressive job of explaining what it is.