ResourcesDiscussion Groups on Yahoo:
Scrum Development Where lots of good discussion goes on. You will find posts from the best in the business. Even us.
Agile Project Management Lots of great Scrum and Agile people here.
Lean Software Development Great discussions of Scrum, Agile and Lean software development.
AgileBusiness Good discussions of things more from the Product Owner viewpoint and the business side.
Extreme Programming Great discussions of Extreme Programming, which is typically essential to truly effect Scrum in software development
Agile-ANN - If you are looking for announcements, meetings, jobs, etc. Worldwide.
Discussion Groups on Google Groups:
Scrum Alliance This Google group has some good discussions.
Discussion Groups on LinkedIn:
Certified ScrumMasters - For CSMs.
Certified Scrum Product Owners - For CSPOs.
Certified Scrum Professionals - For CSPs.