To add to our other lists of "What's New in Whidbey Security", Rudolph Araujo and Shanit Gupta have a nice roundup of new security features posted on the Microsoft .NET Framework Developer Center.  They've got them categorized, summarized, and provide links for more details.  Seems like this is a good candidate for a bookmark for the next time you're wondering how that new feature works -- or even if that new feature exists :-)

Updated 2:36 PM - Fixed link