Recently I noticed that I had missed an important announcement that had been posted to one or two groups on various social networks. Not being someone who likes to be out of the loop, I checked the major networks to find the most important groups about Agile, Scrum and XP.
The "ultimate knowledge center on XP and Agile", which is a great achievement with only 39 people.
Note that there's one network seriously missing from this list: Windows Live Groups, which is because I have not been able to figure out how I'm supposed to search for group names on Windows Live. And besides, if there are any agile people using Windows Live Groups, they're probably 3-year olds, or brain dead.