The largest prize in public interest computing is named after Pizzigati, an early advocate of open source computing who died in 1994. The $10,000 award named after him is given annually by the Tides Foundation to a software developer “who has made an outstanding contribution to the nonprofit community and ongoing efforts for social change.”
From the announcement on Philanthropy News Digest:

Each candidate must submit a completed application. Each candidate must also be nominated by a peer within the public interest computing world or a leader in the nonprofit community who can speak to the personal qualities that contribute to that individual’s leadership, as well as to the product the nominee developed.

The application deadline for 2007 is August 1.
See the Tides Foundation announcement for more information.