It has begun! Apple has just seeded iOS 5.1 to developers. In addition, they have released Xcode 4.3 beta to developers, which is required for testing purposes. Apparently, this update is packed full of crucial stuff.
[quote]iOS SDK 5.1 provides support for developing iOS applications and includes the complete set of Xcode tools, compilers, and frameworks for creating applications for iOS and Mac OS X. These tools include the Xcode IDE and the Instruments analysis tool among many others.
With this software you can develop applications that run on iPhone, iPad, or iPod touch running iOS 5.1. You can also test your applications using the included iOS Simulator, which supports iOS 5.1. There are two Xcode iOS SDK 5.1 images, one for installing on a Macintosh computer running Mac OS X 10.6.7 (Snow Leopard) or later, the other for installing on a Macintosh computer running Mac OS X 10.7 (Lion).
This version of iOS is intended only for installation on devices registered with Apple’s developer program. Attempting to install this version of iOS in an unauthorized manner could put your device in an unusable state.[/quote]