Ladbrokes have apparently suspended betting on the date of the next election.
Betfair are less squeamish and are keeping going.
Some little while ago, the US government had to suspend a betting market on international events, which was running as an experiment to distill received wisdom into a usable intelligence product. In the same way, reading the runes from those betting in the online market, an election is forecast in the next quarter. Labour will win and both Cameron and Campbell will be gone from their leaderships by Christmas. Gordon isn't expected to resign until some time after 2011.
I'm increasingly of the view that we are on for Nov 1 unless something happens to stop it.