Just in case you haven't heard yet and are running WordPress version 2.1.1 (that you've downloaded recently), you need to upgrade your installation because of a security exploit that made its way into the software.

From the WordPress Blog:

Long story short: If you downloaded WordPress 2.1.1 within the past 3-4 days, your files may include a security exploit that was added by a cracker, and you should upgrade all of your files to 2.1.2 immediately.

If you have even a doubt as to if you're running the bad version, go ahead and upgrade to version 2.1.2. Somehow, an individual gained access to the servers where the package is hosted and altered some of the code in the download file. This resulted in a method to bypass any security in place and allow the attacker full control.