This panel was on NASA procurement: Government Acquisition: How Better to Help, or At Lest Not to Harm
The panelists included a NASA "big iron" procurement representative (working on things like Constellation), a SpaceX representative, and Thomas Olson. Only Olson mentioned prizes, although he pushed in general for non-traditional procurement approaches throughout his talk. Here are my brief notes:
Olson advocates something like prize-based methods or something new rather than traditional procurements. He would eliminate the cost-plus culture in favor of a prize or performance based model for smaller projects. His last slide states "Let 1000 prizes bloom".