As mentioned in my Introduction post, I've recently joined the team responsible for the people & groups platform on Longhorn. I was searching around to see what information is out there already on it. MSDN has a good overview article here. The PDC information is also available. There is a PowerPoint overview of the platform here.

What do people think of the platform? What excites you? What do you want to know more about? What would you change? What's missing? We started talking about the Longhorn features early to make sure we have plenty of time to incorporate feedback. We'd love to hear from you. 

[Update: Fixed link to MSDN article - Thanks Chris]