We're excited to announce the availability of the Google Base data API, which lets you write applications that dynamically interact with Google Base. You can insert, edit, or delete items programmatically, complementing existing input means like the Google Base front-end or the bulk upload mechanism. You can also query other users' published content and access their items via the API. This enables you to create domain-specific search applications (or mash-ups) combining Google Base content with other services.
Source: Google Code - Updates: New GData API: Google Base