This acquisition took place in the anticipation leading to the launch of Google games which will be launched later this year. This acquisition has been rumored to be worth $70 million.
Jambool.com is a in-game payment processor which gives game developers the opportunity to implement payments into their game. Jambool.com has been up and running since 2006.
More information can be found here: http://techcrunch.com/2010/08/13/google-confirms-jambool-acquisition/