James Forsyth sums it up:
Fascinating dividing line being drawn between Tories, who say the exit poll means "Cameron in, Brown out" and the Labour team trying to play the "progressive coalition" card. David Miliband says: "Voters have given us an injunction to talk to each other". (As opposed to an injunction to take a running jump.) Blunkett, too, making wooing noises. The Kingswood victory - one of the bellwether seats which indicates a Cam majority - does lead me to suspect the Tories will get to 326 in the end. But not for a few hours yet.
Intrade gives the conservatives around a sixty percent chance of a majority, for what it's worth.