AppNetKit is for Objective-C developers interested in working with the App.net API. The library is asynchronous and uses blocks to notify you of completions. As of late August 2012 this library interfaces with all portions of the app including: token, users, and posts.
Less than a month ago, Google made all public activities available via its "firehose." Last week, the search giant updated the Buzz API again with several interesting features, including a limited firehose, which is calls a "garden hose."
Another day, another API... Keeping on top of all the APIs that have been made public to support the plethora of web services that are available these days can be a full time job. Yahoo thought so too, and so they created the Yahoo Query Language (YQL), which provides access to hundreds of web services with a single SQL like syntax. And now YQL supports Google Buzz.