I'm here in this Republican-leaning Des Moines suburb watching the caucus for the precinct I walked on Tuesday. Some early tidbits, for what they're worth:
Turnout here is very high. There are now more people standing up than who have seats. (Looks like about 60 of the latter, 75-100 of the former.)
At 6:35, I did a quick tally of all the names on the new registration sheets. The sheets allow new registrants to express a candidate preference--not everyone does, but most do. Of the three top candidates, Obama had 24 supporters, Edwards 8 and Hillary 8. Keep in mind that not all of these are former Republicans and Independents. Many are just Democrats who've moved in from some other locale. My informal survey (about 6-8 people) broke down about evenly--half had been non-Democrats, half recently moved here from somewhere else.
All of this has gotten the Obama precinct captain, Monica Green, very excited. The Clinton precinct captain is a little down. I caught her and her assistant engaging in a little gallows humor as Monica gushed about all the new Democrats who were supporting Obama.
Obviously, take all of this with a grain of salt, since we're just talking about one precinct...
Update: The caucus chairman just announced the turnout: 209 registered Dems. "That is a record breaker, folks," he said.