If you downloaded WP 2.1.1 in the last few days, you could have nasty code in your WP install (result of a cracker who got into wordpress.org).
Since I upgraded only hours after the inital announcement of WP 2.1.1 and not in the last few days, I don’t think I’m affected.
Nevertheless, this blog is updated already, and all the other WP blogs I’m responsible for (FW, GB and YMM) are down temporarily and are being updated right now.
If you are running WP 2.1.1, upgrade asap.
UPDATE: every site I’m involved with is updated to 2.1.2 and back online. Now I’m off to bed – it’s already past midnight…