The Guild blog got hijacked by those spammers too. The issue seems to be old WordPress files that have been hanging around from previous versions and never got updated because…well, they’re not used any more. So if you have a self-hosted WordPress blog that has been updated from an older version, check your files. Wiping all the WordPress files and starting with a fresh install might be a good idea.
In closing, I only have this to say…bastard spammers.