Apple has released iOS 6.1 beta 3 build 10B5117b for developers, which is compatible with iPhone, iPod touch and iPad. iOS 6 beta 3 brings improvements and bug fixes related to Passbook app, Mapping app, Safari etc.
Registered Apple developers can download latest iOS 6.1 beta via iOS Dev Center.
If you are running previous iOS 6.1 beta version on your iDevice then you can grab iOS beta 3 as over-the-air (OTA) update by navigating through “Settings” > “General” > “Software Update” > “Install Now” on your iDevice.