Microsoft Declares "Today, we take our pursuit a step further. After publishing notices in two Russian newspapers last month to notify the Rustock operators of the civil lawsuit, we decided to augment our civil discovery efforts to identify those responsible for controlling the notorious Rustock botnet by issuing a monetary reward in the amount of $250,000 for new information.

Source
http://www.zdnet.com/blog/hardware/microsoft-offering-250000-reward-for-rustock-botnet-info/13741