Sophos recently released, Sophos Atni-Rootkit, a free product that finds and removes any rootkit that is hidden on your computer. Be sure to grab the user manual and release notes.
This got me thinking about other rootkit detection tools. The first one I’ve used is RootkitRevealer from Sysinternals. There’s F-Secure BlackLight. Alas, it’s not free. The stand-alone BlackLight expiration has been extended until 1st of October 2006. An integrated BlackLight engine has been included in the F-Secure Internet Security 2006 suite.
There are probably others but that’s all the products I found from major vendors.