Apple announced the Beta 5 of iOS 7 earlier then expected probably to make up for the time lost due to developer center downtime but they have yet again surprised everyone by releasing the 6th Beta of iOS 7 much earlier then expected.
As you can see, its OTA weighs at a meager 12.7 MB which means that it doesn't bring a whole lot of changes with itself. The only fix it contains is to an issue with iTunes in the Cloud which, apparently, required some work-around to be applied to it.
As this is a very early Beta release with a very targeted agenda, it looks as if this was an emergency release meant only for this fix.
Note:- While Beta releases have always been available only to developers (which requires a 99$ / year paid account), you can click here to find out how to install iOS 7 Beta on your iDevice.