Okay, i'm gonna go out on a [slight] limb here and predict that Kerry will win.
My intuition is younger (18-29) voters with cellphones may not have been sampled accurately in pre-vote polling, and lean more towards Kerry than Bush. A recent Zogby poll of young Rock-the-Vote participants via SMS would seem to confirm this, citing Kerry over Bush with a 55% to 40% lead among those voters.
Both campaigns have been working hard to register new voters and get out their base, and a tight race should encourage more people to vote. If the youth vote shows up in larger numbers than in the past, very possible they could swing the election towards Kerry by more than polls to date have been indicating. However, similar effect could also happen on the Bush side mobilizing through churches to get more evangelical and religious right members out voting for the first time.
Overall, recent polls seem to be breaking Kerry's way, with slight leads over Bush in the big battleground states of Ohio, Pennsylvania, and Florida -- although Florida again appears so close that any election day shenanigans could once again provide a field day for lawsuits and legislators.
For an interesting view of up-to-the-minute electoral vote predictions and graphs, check out: