Yesterday Apple released iOS 4.1 beta 3 for developers. Build number is 8B5097d for the firmware and 10M2308 for the SDK. Here is what's new in beta 3:

• A revised API that allows applications to have an access to contact thumbnail pics;
• Media playback enhancements, which include new classes in AV Foundation, related to batched playback, writing/reading and file compression;
• New features of Game Center: now players can track their in-game achievements and game scores on leaderboards and find teams for group play. But it was also found that Game Center is no longer supported for iPod touch 2G and iPhone 3G, though it is unknown whether it is a permanent change or not.

Final release of iOS 4.1 is expected to be shipped in September or October.