Yesterday, Apple released the second beta version of iOS 4.1 to developers. About two weeks ago, Apple had released the first beta version of iOS 4.1 for developers which had some minor changes from iOS 4.0. The update was much anticipated as Apple had announced in the press conference of iPhone 4 that they would fix some issues with the proximity sensor with the next software update. The version of the iOS 4.1 beta 2 build is 8B509b and is available for iPhone 4, iPhone 3GS, iPhone 3G, iPod touch 3rd generation and iPod touch 2nd generation.
Looks like iOS 4.1 beta 2 fixes only some minor bugs without any big change. After the launch of iPhone 4, many users had reported proximity sensor issues with iPhone 4 which were causing problems during their calls. It was expected that Apple may solve proximity sensor issues with this update but it looks like the fix is not in this release.