If you’re a WordPress user and are using version 2.1.1 it is crucial that you upgrade to the latest version (2.1.2) – particularly if you upgraded in the last 3-4 days. The reason is that there has been a hacker compromise that version and add/change code.
For further details see the WordPress Blog
PS: Thanks to the many people who emailed me about this. I did see it first on the WP blog before checking email this morning.