Now especially with Convergence coming up, XRM is really taking off. We've been XRM-ing around here for close to 2 years now (wow, really, TWO YEARS). And if I think about it, we've been XRM-ing longer than people have been thinking XRM even existed. We integrated CRM 3.0 with a cool internal app for commercial real estate eons ago, had maps in CRM 3.0 before Balmer showed that one off, then someone coined "XRM" and a movement was born.
All of that to get to this, a chapter from our XRM book is on MSDN for download. (thanks Jim Glass). Go have a read, it's a great chapter on Developer and Team workspace. There's a link to buy the book from Amazon, it will also be at the Convergence bookstore.