Apple has just seeded iOS 4.1 GM Build, along with SDK for iPhone 4, iPhone 3GS, iPhone 3G and iPod touches. This is for developers only. Only members enrolled in the iPhone Developer Standard or Enterprise Program can access these bits of by signing into Apple Developer Connection.
This new build includes fix for Proximity Sensor and Bluetooth, performance improvements for iPhone 3G, HD video upload over WiFi and Game Center. Also included is the new HDR (High Dynamic Range) photos option for iPhone 4 users which Steve Jobs demonstrated earlier in his keynote address.
The first Beta 1 of iOS 4.1 was released on July 15th, Beta 2 was released on July 28th, while the Beta 3 was released last month on August 4th. Public availability of iOS 4.1 is due next week. iOS 4.2 for iPad, iPhone and iPod touch on the other hand will be available in November of this year. More info about iOS 4.2 can be found here.
Download iOS 4.1 GM Build and SDK