It's a treasure hunt with a difference: Google is trying to lure private investors into building lunar space craft by dangling a $20-million prize for the first non-governmental flight to the moon. 

It's not certain whether there will be any takers, because an enterprise of this magnitude is both complex and expensive.
The prize is being offered together with the XPrize Foundation.
The unmanned craft that wins the race must land on the moon's surface and take at least 1Gb of still and video images that will be shown on the Google site.
There is a deadline for the project; if no-one has won the purse by the end of 2012, it will drop to $15-million until the end of 2014, at which point it will fall away.