Duane Forrester, Bing's version of Matt Cutts (on some level), posted this long blog post on the importance of keywords in domain names on rankings.
In short, he said it is a myth that keyword rich domain names have a direct positive impact on rankings. He isn't saying it has a negative impact but he is saying that Bing and other search engines have other means and signals of determining ranking and relevancy outside of the keywords used in a domain name.
So he said don't think that if you own blue-widget.com that you will rank well for [blue widget] - you need other factors to convince Bing that you deserve to rank for that keyword phrase.
A WebmasterWorld thread has a couple SEOs mocking this saying it is not true, at least with Bing.
My own very limited modest personal experience* is that they are much more devoted to exact matches than the #1 search engine is. If you search for "furry brown widgets" you will be pointed to furrybrownwidgets dot com, even if they have no idea what the site is about.
Forum discussion at WebmasterWorld.