Well, sort of. The latest Newsweek poll gives Obama the lead among likely Democratic caucus-goers, with 28% over Hillary Clinton's 24% and John Edwards' 22%. Among all Democratic voters, though, Hillary still enjoys the lead with 31% over Obama's 25% and Edwards 21%.

Even among "likely" caucus-goers, Hillary's support is more solid, with 55% of her voters saying they "strongly" support her, versus 41% for Obama and 37% for Edwards. (Scroll down to 5a and 5b for the Democratic numbers at the link).

It is often said - sometimes by me - that early polls are meaningless. It's true they cannot be said to be predictive of the nominee, or even the state winners, before any votes are cast. Just ask Ed Muskie, Gary Hart, and Howard Dean. This applies mainly to the Democratic race, though - the last time Republicans failed to nominate their clear frontrunner was 1940 with Wendell Wilkie.

Early polls do have other "meaningful" effects, though. They attract media attention, and can help generate or sustain enthusiasm in the campaign and among supporters. They also make it easier to solicit donations, especially if some forward progress is evident. So while these polls won't tell us who will win, they can certainly affect attitudes and impressions enough to narrow the field.

That said, if there is any one state in which the polls mean less, it is Iowa. Iowans, especially the Democrats, delight in defying the national media expectations. Having the lead in the polls coming into the caucuses can actually work against a candidate because of this contrarian nature.

And Iowa isn't about opinion polls for a much bigger reason: this isn't an exercise of stopping by the precinct at your convenience between 7 a.m. and 7 p.m., punching buttons or pulling levers, and going on your way. In Iowa, you are committing to driving to some poorly-heated location on a winter night to sit between 7 p.m. and roughly 10 p.m. (longer if that's what it takes), listen to various speeches, and form into groups supporting candidates every half hour or so. The candidates with the fewest supporters are then eliminated, and the groups reform - after a suitable period for lobbying your neighbors to join your group. This goes on until one candidate captures a majority, and all candidates lacking enough support to win at least one delegate from the caucus are eliminated. All this time, they still haven't figured out how to turn on the !#@?% heat.

No, Iowa is about the most dedicated supporters and the best organization. A certain percentage of Iowa Democrats will attend no matter what - mostly an over-50 demographic, which tends to favor Clinton. But it is organization - getting one's supporters to actually go to their caucus - that makes the difference. Obama has 31 local offices - twice that of Clinton or Edwards - and Edwards has been organizing Iowa since 2003 and has strong labor support there. Whatever the polls say now, or even the day before the caucuses, the campaign which can motivate its people to show up will win.

Still, it's better to be moving into the lead in the polls than to be fading away.