Apple has just released iOS 4.2.1 GM seed (Build: 8C148) for iPhone 4/3GS/3G, iPod Touch 4G/3G/2G & iPad (Wifi+3G) to developers only. Apple rolled out an updated version of iOS 4.2 GM seed last week as well. This is however a completely new firmware update identified as iOS 4.2.1 by Apple.
It's an interesting move from Apple as people were expecting iOS 4.2 final build instead of another GM seed. As per Macstories, an inside source have confirmed that iOS 4.2.1 GM is released to fix issues with Exchange and the audio devices. These issues were also documented on the official Apple support forum.
It has also been rumored that Apple might release iOS 4.2.1 publicly next week which indicates that Apple might skip iOS 4.2 altogether. There is no official confirmation, but it's quite possible as it gives Apple the room to release new firmware with almost all bugs and performance issues fixed.
Like other GM seeds, this firmware is also meant for developers only, people with registered Apple Developer account can access this update by signing into iPhone Development Center.Contact Us for News Tips, Corrections and Feedback