This is just common sense stuff, but I’ve come across two sites this week with the same vulnerability Matt Cutts blogged about recently, and in both instances it was negatively impacting their rankings because Google was indexing pages on their domains which appeared to be XXX rated content…

If you’ve noticed that your rankings in Google seem to be affected, you might consider a few searches on your site to see if anyone has injected spammy or porn content on your site. If your domain was example.com, you might want to run a few queries such as [site:example.com porn] or [site:example.com biaxin] or [site:example.com viagra] to see whether you run across unexpected results. [read the rest].

One of the sites I’ve seen suffering this was a Mobabletype blog so might be worth checking into especially if you run MT.