The Des Moines Register published its Iowa Poll yesterday, its first survey of caucus-goer leanings since May. The results are important for both sides.

Among the Democrats, Hillary Clinton has rocketed to first place -- up to 29 percent, from 21 percent in May. She's basically traded places with John Edwards, who's dropped from 29 to 23 percent. Barack Obama has stayed relatively constant -- he polled 22 percent. Clinton's spurt matters because while the former First Lady has consistently led in national polls, Obama and Edwards have staked their competitiveness on their leads in Iowa. According to the Register, this poll tracks other recent surveys that show Clinton building a lead in Iowa.

The bigger news is on the Republican side.

Romney continues to hold a big lead at 29 percent (it was 30 percent in May), but TV star and former Tennessee senator Fred Thompson has rocketed to second place, with 18 percent. John McCain had 18 percent, but he's since plummeted from second to fifth place. Rudy Giuliani has fared nearly as badly: his 17 percent share has dropped to 11 percent, just behind an improving Mike Huckabee. Worse for Hizzoner, nearly half of Republicans have already ruled him out, a much higher number than the three other leading candidates. In the last week or so, I've heard some social conservatives predict these reversal of fortunes for Giuliani and Huckabee -- notions that were promptly dismissed by the professional pundits. Heh. (Ron Paul, despite his popularity on the internet -- and apparently among Agenda readers -- polled only four percent.)

Of course, all this should be taken with a grain of salt. The poll has a five percent margin of error. And three-quarters of the likely Republican caucus-goers, and half of the Democrats, say they might still change their minds.

Read the Register's results here.