The USPTO and Google have entered a two-year agreement to allow Google to provide bulk patent and trademark data to the public, according to a USPTO press release dated June 2.
The agreement requires Google to host the data at no charge and without modification. It appears that the data is being offered in weekly segments, at least for the last ten years or so. Older data (pre-1996) is offered in yearly files.
This is a great day for public access to patent information, especially for people who want to mine patent data or build large patent databases. I'm not sure how useful it will be for average users who might want to download a much smaller, targeted set of data.