I'm going to get into this a bit in my upcoming print piece, but it's worth considering that Nevada is, like Iowa, a caucus state, where organization tends to be rewarded and where, as Obama campaign manager David Plouffe argues, his team is incredibly well-organized. (Though I've heard that team Clinton has a solid organization there, too.)
Another thing to keep in mind about Nevada: Everyone talks about the importance of the culinary workers endorsement, which Obama just received. Also important is the fact that Bill Richardson plans to fight on there, and may therefore take some of the state's Hispanic vote out of play. (When things were looking grim for Hillary this weekend, you heard a lot about her Hispanic firewell. But surely Richardson, the Hispanic governor of a nearby stage, is going to have something to say about that.)
Update: Well, that lasted exactly four hours...