If you've just recently upgraded to WordPress 2.1.1, you're going to need to upgrade again! If you haven't upgraded to 2.1.1, don't do it! 2.1.2 is a MUST DO UPGRADE. The reason is because WordPress found out that someone cracked the 2.1.1 files and modified the code to do evil things. Funny enough, the Root of All Evil himself told me about this. I was wondering if I should take the warning seriously until I read it on WordPress's own site...
It was determined that a cracker had gained user-level access to one of the servers that powers wordpress.org, and had used that access to modify the download file. We have locked down that server for further forensics, but at this time it appears that the 2.1.1 download was the only thing touched by the attack. They modified two files in WP to include code that would allow for remote PHP execution.
This is the kind of thing you pray never happens, but it did and now we’re dealing with it as best we can. Although not all downloads of 2.1.1 were affected, we’re declaring the entire version dangerous and have released a new version 2.1.2 that includes minor updates and entirely verified files. We are also taking lots of measures to ensure something like this can’t happen again, not the least of which is minutely external verification of the download package so we’ll know immediately if something goes wrong for any reason.
Make sure you download the update right away and patch your installation. If you have any information on how this happened, or have any questions or concerns about this, WordPress is asking you to email them at: firstname.lastname@example.org