Not sure if I have seen this mentioned before. Dan Thies noticed Googlebot's wildcard robot.txt support:

Google's URL removal page contains a little bit of handy information that's not found on their webmaster info pages where it should be.

Google supports the use of 'wildcards' in robots.txt files. This isn't part of the original 1994 robots.txt protocol, and as far as I know, is not supported by other search engines. To make it work, you need to add a separate section for Googlebot in your robots.txt file. An example:

User-agent: Googlebot
Disallow: /*sort=

This would stop Googlebot from reading any URL that included the string &sort= no matter where that string occurs in the URL.

Good information to know if your site has recently suffered in Google due to duplicate content issues.

Dan also recently an SEO coach blog on his SEO Research Labs site.