Besides releasing Mac OS X 10.5.3 today, Apple also released a new version of the iPhone SDK (Beta 6). No details have been posted. Apple should be wrapping up development of the iPhone SDK which is expected to be complete by late June. Apple will be covering many aspects of the iPhone SDK during their Worldwide Development Conference which starts on June 9th.
Previous versions of the iPhone SDK and Beta 2.0 Firmware have revealed new features coming to the iPhone, including Geotagging, 3G preferences, Chinese handwriting recognition, and Photo saving,