By submitting, posting, displaying, or transmitting Data on or through the Service, you give Google permission to process your Data for the sole purpose of enabling Google to provide you with the Service in accordance with its privacy policy. You hereby grant Google all licenses to your Data necessary to process the Data and provide you with the Service in accordance with its privacy policy. As a part of the Service and through provided interfaces, Google may allow you to remotely access, view, and download results of the processing of your Data. (via http://code.google.com/apis/predict/docs/terms.html)
I imagine that they might claim the right to use your data anonymously to improve their algorithms, much like they do for your personal data in their other apps. I mean, what better way to refine their supervised learning algorithms than via an endless supply of training sets? But I hate wading through legalese, anyone have any insights?