Did Gordon Brown just do what I think he did?
I think that settles the leadership debate.
Edit: it's official. Gordon Brown has resigned, and as I type the UK is without a Prime Minister.
And now we have a new Prime Minister: David Cameron has been invited by the Queen to form a government.
Note to non-Brits: we don't have the "lame duck" period that other countries have. The handover of power is now basically done, David Cameron will move into Number 10 Downing Street this evening, and over the next day or so he'll sort out his new cabinet. The next highlight is the Queen's Speech in a few weeks wherein he'll set out what the Conservatives intend to achieve over the next few months, and then Parliment will have what's effectively a vote of confidence in our government.
There's still the grand question of just what the government will look like - the Tories are the biggest single party and are only about 20 seats short of an outright majority, so they could end up forming a minority government without the Lib Dems (though that's risky, as then a Labour/LibDem alliance could block the Tories).