Apple has just released iOS 7 beta 3 to developers. It's available both as an over the air (OTA) download and, if past is prologue, it'll be available soon from Apple's developer web site (assuming, of course, you're a registered iOS developer).
Apple's public information about iOS 7 beta 3 indicates bug fixes and improvements. iOS 7 is covered under Apple's Non-Disclosure Agreement (NDA) with registered developers as Apple prepares its release to the general public this fall. Registered developers should check the release notes before updating.