Google has released a new video about configuring URL parameters in Webmaster Tools. It's about 15-minutes long, and features Google Developer Programs Tech Lead Maile Ohye discussing the how to help Google crawl your site more efficiently, and manage a site with URL parameters.
"URL Parameter settings are powerful," says Ohye. "By telling us how your parameters behave and the recommended action for Googlebot, you can improve your site’s crawl efficiency. On the other hand, if configured incorrectly, you may accidentally recommend that Google ignore important pages, resulting in those pages no longer being available in search results."