Use Targeted Keywords in URL: A month ago, I questioned the use of keywords in URLs. These folks did a test. They put a garbage word in the URL of a page. They used the word nowhere else on the page or in the linktext to that page.
Before we started our test, we searched for rkpatjfg in Google, MSN beta, Yahoo!, Ask Jeeves, Lycos, Teoma, WiseNut, Exalead (AOL.fr) and Voila. There were no results on these search engines.
Results […] Google, MSN (beta), Yahoo! and Exalead take into account the words in the URL. […] The other search engines (Ask Jeeves, Lycos, Teoma, WiseNut and Voila) have not yet crawled our webpages
This proves that search engines take it into account, sure. But I maintain that this is much less pressing than 90% of the other issues you find on the average Web page. If you’re prioritizing your SEO work, I still think there are a dozen things that stack up above URLs in the list.
Via Anders Midtgaard in a comment to that original post.