Here’s the announcement from SFgov.org:

We are pleased to announce the release of our Open311 API. The design is a result of a collaborative effort between cities, non-profits and developers. We look forward to seeing what you produce.

You can request an API key from their website and read-up on the Open311 API spec and developer resources here on this website. If you have any questions or comments, please leave them here or on the mailing list. We look forward to working with the developer community and seeing some amazing Open311 apps!