Direct from the source:

April 23, 2007

For the fourth straight week, Illinois Senator Barack Obama (D) has gained ground and he has finally caught New York Senator Hillary Clinton in the race for the Democratic Presidential nomination. It’s now Obama 32% Clinton 32% and former North Carolina Senator John Edwards holding steady at 17%. New Mexico Governor Bill Richardson is a distant fourth at 3%. Senators Chris Dodd and Joe Biden each attract 1% support. So does General Wesley Clark.

It makes a good headline however every other poll still shows Hillary as the leader:

That being said, Obama has had a somewhat steady trend towards Hillary from RCP:

Still, Hillary is the rightful owner of the nomination thrown. Obama, the Luke Skywalker of the Democratic universe, is hot on her heels eagerly trying his best to overthrow the empire and lead the Hollywood rebellion. John Edwards is that guy somewhere near the back dreaming the impossible dream.