updated 01:20 pm EDT, Mon July 29, 2013
Changes so far unexplored
In keeping with earlier rumors, Apple has started seeding iOS 7 beta 4 to developers. Because the code has only just been released, any changes have yet to be discovered. The rumors suggested, though, that beta 4 would implement bugfixes, graphical and UI enhancements, and "a couple of other updates."
One source further indicated that only two more iOS 7 betas will be issued before the firmware is complete. Apple may have relatively little time left to work on it; the company is widely expected to launch iOS 7 sometime in September alongside new iPhones, leaving just the month of August to fix any major polish or feature difficulties.
Registered developers must download beta 4 as an over-the-air update or wait for it to appear at the Developer Center.