[Update @ 3:44 PM PST]
As of 3:34 PM PST, impact has been mitigated, and site experience should no longer be degraded. Thanks for your patience!
We're aware of an issue where the MSDN Social Profile pages (for example, http://social.msdn.microsoft.com/profile/alan%20chen%20-%20msft/) are rendering incorrectly. We're actively working on it, and will provide updates via this blog post.
The MSDN Service Delivery Team