Apple has released the second beta version of iOS 6 to developers today. The update went live less than an hour ago. Developers with iOS 6 beta 1 installed on their devices can download the update over the air directly to their devices.
It's not clear what has been changed with the new beta version. All Apple says is that it includes bug fixes and improvements. The update is 322MB in size. Apple has not yet updated the developer site with further details on the new beta.
The first beta of iOS 6 was released shortly after the WWDC 2012 keynote two weeks ago. According to early reports the new features were generally great, but the system tended to be fairly buggy and unstable. This release presumably fixes some of the instabilities of the previous version. It's also possible that it adds new features, but we'll have to wait until the developers start digging around in it to know for certain.
The final version of iOS 6 is scheduled to release sometime in the fall. Though Apple didn't say so during the keynote, iOS 6 will release at the same time as the new iPhone, which has been widely rumored to be coming in October.