Sidewiki - Comment on any website with this Google app

Yesterday Google announced the release of Sidewiki, a universal web page commenting system that allows anyone with the Google Toolbar to add comments and feedback on any web page.

But that’s not all. Google has also announced the release of the Sidewiki Data API a RESTful API that allows developers to access information maintained in Sidewiki about a particular web page (or information by a particular author).  The new API returns XML and can be accessed by Java and JavaScript client libraries.

As with its other APIs, Google has made various types of information available to developers, including a developer’s guide, a Google Group, client libraries and sample code, and an issue tracker.