How do you make sure that your WordPress blog is safe from the Blackhole exploit?

I got a mass email from one of our vendors warning that their WordPress blog had been compromised using the “Blackhole exploit” and that they apologized for any spam that may have been sent as a result. It didn’t go into any details beyond that. We have a WordPress blog as well and I’m not sure how the Blackhole exploit works.

Story added 15. August 2012, content source with full text you can find at link above.