The Google Sites Data API lets developers access, publish, and modify content within a Google Site. The API is available to both Google Account and Google Apps users.
Here are some of the things you can do with the API:
* Retrieve, create, modify, move, and delete pages, comments, attachments, and other content.
* Review the revision history across the Site.
* Monitor all add, modify, and delete activity for a Site.
* Upload/download attachments and files.
* Create customized gadgets for your users."