Moments ago Apple released iOS 5.1 Beta 3 for Developers. The new Beta came after along time. The Beta 2 was released lat year in second week of December, where as the third beta with build 9B5141a is released today after a month. We expected a new iOS release by Apple.
According to macrumors, the update is only available by OTA (Over the Air) update so far for the Beta testers. The update will start to roll out soon on the Developers portal soon.
As soon as the iOS 5.1 Beta 3 rolls out on Developers portal, we will update you with the complete change-log. We can expect some battery improvements in this build by Apple for users on iPhone 4S and some improvements made to SIRI by Apple. Till now the update is only available for people who are on iOS 5.1 Beta 2. They can update to new beta 3 by OTA.