In iOS 6, new core bluetooth classes such as CBPeripheralManager and CBMutableCharacteristic were introduced. However, I've looked at core bluetooth documentation and can't find any documentation on the new classes. Can someone point me in the right direction?
The best way, in my opinion, is to just look at the header files in Xcode. Assuming you've added CoreBluetooth.framework, just expand that, then Headers, in Xcode. The headers inside are all documented in the same way as Apple's Class References online.
To make it even easier, I personally decided to download Doxygen, which can compile HTML/PDF/etc. documentation straight from those header files. If you go about it that way, the headers are stored at /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS6.1.sdk/System/Library/Frameworks/CoreBluetooth.framework/Headers.