The result of the vote for the 2016 host city is expected at around 1740 BST today.
Selection takes place via secret electronic ballot of all 106 IOC members. Only 98 members will be eligible to vote in the first round, with seven members coming from countries with bidding cities having to abstain, plus Jacques Rogge, the IOC president, who is neutral.
The winning city requires more than half the vote. This is unlikely to be achieved in the first round, so the city with the fewest supporters will be eliminated and the votes recast. This will be repeated until an absolute majority is reached.
The elimination process places greater importance on members’ second and third-choice cities. If Madrid is eliminated after Tokyo but before the other two, for example, this could help Rio de Janeiro, which would be expected to pick up the Hispanic votes.
http://www.timesonline.co.uk/tol/sport/olympics/article6858263.ece#So we'll hear in about 2 hours.