The first and only exit poll has been reported by the BBC:

Seats in the House of Commons:

Conservative: 307

Labour: 255

Liberal Democrat: 59

 If this result holds it means that there will be a hung parliament as the Conservatives are 19 seats short of a majority. Keep in mind, however, that exit polls everywhere are notoriously unpredictable. Though the U.K. exit polls got it right in 2005, 2010 is a closer election and several factors make an accurate prediction all the more difficult: First the wonks-that-be are working off of national data, which may not be accurate in a parliamentary election in which people vote district by district. Second, only about one in six voters respond to exit pollsters. Third, while the exit poll may get the share of the national vote correct, it may miscalculate the number of Commons seats, due to the peculiarities of the British system.