It must be at least a year since I started a thread, but here goes. On the Democratic side, whether for Obama, Clinton, or even Edwards, to an extent, there seems a genuine adoration for those candidates among their supporters. Obama voters really believe in Barack Obama; they vote for him because they want to see him elected President. Hillary's not quite at that level, but clearly to many demographic groups (mainly ones that aren't represented on this board), she represents a unique candidate (as a woman) and thus receives devoted support not seen since at the very least, her husband back in the 90s. Supporters of these candidates really are FOR these candidates, not against anyone else.
In 2004, I got the sense no one really cared about John Kerry. The election may well have been George W. Bush vs. Generic Democrat. Kerry was entirely unspectacular; he didn't do anything terribly stupid to lose the campaign (sure, he made mistakes, but nothing on a George Allen level), but he didn't help himself much either. His platform was standard liberal fare - a Massachusetts senator, yes, but not a radical socialist by any means. He didn't represent a larger vision for America - he was just the candidate Democrats decided had the best chance to defeat Bush. In the end, Bush received 286 electoral votes, the Democrat received 251. Kerry was just a name next to the letter (D).
Bear in mind I'm only 17; I've only experienced 2000 and 2004 before 2008. But this time around on the Democratic side, there seems actual excitement for our own candidate, whomever it may be. There was still tremendous excitement among Democrats in 2004; Kerry did fine fund raising wise and turnout largely increased, although not enough among the young voters he needed. We still had energy, but it was completely anti-energy. Few gave their time with the goal of getting John Kerry in the White House; people stood outside voting booths with signs, made phone calls, and went door-to-door to defeat Bush. Even in 2006, the entire emphasis seemed to be on getting rid of those pork-barreling, corrupt, Mark Foley-like Republicans. As long as there was a (D) next to the name of their opponent, vote for him/her.
This is different - Obama and Clinton, for different reasons, are two very inspiring candidates of whom the party can rally around and genuinely support. (Perhaps I shouldn't say that about Clinton, judging by the hatred most Democratic forumites very openly spout)