Google is releasing an API for its Webmaster Tools.

The API provides the ability to manage sites (retrieve, add, verify, and remove websites) and work with sitemaps (retrieve, add, remove). This will be immensely useful for those web professionals that need to update multiple sites on a regular basis. Although the current API offers a limited subset of all the functionality (the ability to retrieve queries on the data - links, crawl errors, etc.) that the online Webmaster Tools provides, you can get started with the Developer's Guide for the Webmaster Tools Data API immediately.