Apple Insider reports that Apple has released iOS 6.1 beta 4 to the developers for testing

iOS 6.1 beta 4 is now available to developers as an over-the-air update. The pre-release update, identified as build 10B5126b, can be accessed in the Settings application by those already running iOS 6.1 beta software.

The latest beta version of iOS 6.1 is said to contain bug fixes and improvements. It is not finalized and is not available to the public.

In addition, Xcode 4.6 Preview 4 and Apple TV software update beta 3 were also supplied to developers on Monday. In addition to Software Update, they can also be accessed from Apple's developer website.

  Apple seeds iOS 6.1 beta 4, plus new Apple TV and Xcode betas to developers