iOS 6 Beta 4 is now available for Developers
It seems that after 3 weeks of the latest release of iOS beta 3, Apple has provided a new beta version for developers. The update comes as built 10A5376e, being available for iPhone 3GS, iPhone 4, iPhone 4S, iPod touch 4th generation, iPad2 and the new iPad. 
Developers could get full advantage of the beta update through Over the Air. Other releases that are worth taking a glance are Xcode beta and Apple TV iOS 6 beta. The operating system update focuses especially on bug fixes and performance amplification. 
Apple users are waiting eagerly for the release of iOS 6 this fall, expected to be launched with the latest generation of iPhone. 200 new features will be possible with iOS 6, some of them being Facebook Integration, Google Maps, Do Not Disturb, Lost Mode, 3D Flyover and so on and so forth. 
9to5Mac has provided bug fixes and some new features of the new updates, namely Address Book, Apple TV, Dictionary, Game Center, iTunes, iCloud, Location, Maps, Newsstand and Passbook etc.
Source: 9to5Mac
Related posts:
iOS 6 Beta 2 Released to Developers
iOS 6 beta versions coming along instead of iOS 5.1.2
Apple Updated iCloud Website for Developers
New pictures with iOS 6 beta 3
Deep Facebook integration within iOS 5.1 beta 3
iOS 6 Beta 2 Released to Developers 
iOS 6 beta versions coming along instead of iOS 5.1.2 
Apple Updated iCloud Website for Developers
iOS6 Beta 4 users may find that Passes disappear from their Passbook or the some of the images appear funny. We’ve integrated the Beta 4 changes into the sample passes now, and just doing the same with the PassKit Pass Creator.
I suggest if anyone wants to test Passbook in Beta 4, the best thing to do is download the sample Passes again from PassK.it/samples. To test the API and push updates, simply re-use your API key from the Starbucks sample.
Hope this helps.