I found a nasty hack installed on multiple wordpress sites today. Wrote a bunch of emails back and forth with one site owner in hopes to help him figure out the problem.
Wrote all the details of it on my blog
If you're infected with this and need help let me know - I'd like to solve this one to get some wordpress street cred above discovery - speaking of which, anybody seen this one before - I find no mention of it anywhere.
Amongst other things (most notable) this one changes your Titles and links to things like "ONLINE Chloramphenicol FOR SALE" but only under certain circumstances so it is VERY DIFFICULT to detect!
Details in the blog post.