With all the new features Google Analytics has been unrolling since version 3 launched in August, the Google Analytics was in need of a new API. Now, developers have it.
The new Core Reporting API has two versions. Version 3.0 is an all new release that contains new libraries for other languages like PHP, Ruby, and Python. It reduces the size of the data outputted 10 times more efficiently than previous APIs. The version 2.4 API is a legacy release to maintain compatibility with the previous Data Export API version 2.3.
Developers will find significant changes in the v. 3.0 API, starting with authentication through the OAuth 2.0 format, but also in the use of JSON format for data output and absolutely no backwards compatibility with the previous version 2.3. The 2.4 release will provide some of the backwards compatibility, but the API team highly recommends migrating to the new 3.0 version.
If you develop custom apps or interfaces using the 2.3 API, you'll need to update within six months. The XML requests, Data Export API Account Feeds and all configuration data will be going away at that time.
Google Analytics has seen many changes this past year. With new social reporting already announced for 2012, the features will continue to roll out. This API will help developers keep up with them and help Google make the new features more accessible.