NIST has opened up a National Vulnerabillity Database, also available as an XML feed.  I love the fact that all of the available info will be in one place, although I do fear that it will re-open the "what's more secure" arguments that have been running for several years.

Link: http://nvd.nist.gov

Story:  http://www.fcw.com/article89911-08-15-05-Print