The wordpress group has released an update to Wordpress to address some issues. From the release notice:
We have a security update release now available for both the 2.1 and 2.0 branches of WordPress now available for immediate download. This update is highly recommend for all users of both branches.
These releases include fixes for several publicly known minor XSS issues, one major XML-RPC issue, and a proactive full sweep of the WordPress codebase to protect against future problems.
Glad they are on top of things, too bad I have to update half a dozen sites now 