Bart De Smet's on-line blog (0x2B | ~0x2B, that's the question)
Get it directly from Mr Monad - Jeffrey Snover - on http://channel9.msdn.com/ShowPost.aspx?PostID=25506. For a short intro on what it is in the format of a PPT, refer to the PDC slidedeck on http://download.microsoft.com/download/3/8/1/38198a72-294d-46c3-93ba-faee5cf85d00/ARC334.ppt.
I've been playing around with Monad for quite some time now and it's really cool (and useful!). I hope I'll find the time to write a bit more about it shortly on my blog or somewhere else. I'll keep you posted.