When Google announced on March 13th that it would no longer be supporting the CalDAV application programming interface (API), developers were not happy. In early June, Google reconsidered its position and re-opened CalDAV and, to top it off, Google said they’d be opening CardDAV’s API as well.
CalDAV, for the non-programmers among you, is an open extension to the Web Distributed Authoring and Versioning (WebDAV) standard for Web-based calendar services. It’s used in Apple’s iCal; Mozilla’s Calendar Project-based programs; and it will soon be available in the next update to Windows Phone 8. It’s as close to a lingua franca for calendaring applications as we have today.