The most recent beta was given to developers in the middle of last month and besides Siri's new fearure, users are now asked to set up security questions for iCloud when setting up their device for the first time. In November, another leak revealed that Apple would make it easier to report a problem with Apple Maps in iOS 6.1 while at the same time, the music controls on the lock screen were easier to use thanks to better spacing of the controls. Meanwhile, developers have received an enhanced MapKit for the latest iOS build, allowing third party apps to look for addresses based on a particular topic or point of interest.
So far, iOS 6.1 has been compatible with the Apple iPhone 3GS through the Apple iPhone 5, the second, third and fourth-generation Apple iPad, Apple iPad mini and the fourth and fifth-generation Apple iPod touch.
source: iFun (translated) via AppleInsider