The 2012 Summer Olympics will take place in London and the city is already admitting their turn to host will not be as extravagant as Beijing [1]. Britain has nothing to feel badly about; this year's Olympics were the most expensive in history [2], and it's unlikely another city would top that.

Britain is in the midst of a credit crunch that didn't exist when they won the Olympic sweepstakes three years ago. The government has already expanded their original budget by $13 billion, and says the current $17.4 billion budget is all they can afford. Unfortunately, there's no guarantee the expense will pay off — a Merill Lynch study showed that of the last 11 Olympics, the Games caused financial problems for 10 of the host cities.

Source [3]