So we've noticed an issue with the iOS 6.0 simulator … when running some iOS test code, and while trying to connect - disconnect from the target hardware (nRF51822 EVK), the iOS 6.0 simulator will not release the BLE connection for about 60 seconds. 
 
Annoying, but not fatal. 
 
Problem is, I was trying to debug some new nRF51822 firmware yesterday and in the end couldn't tell if it was the BLE firmware or the simulator. Long story short, when running the same iOS code in the iOS 5.1 simulator, we get the expected / correct operation (that being when the iOS code disconnects, the simulator immediately disconnects from the hardware).  
 
My setup is 2011 13.3" 1.8GHz i5 MBA running X.7.5 using Xcode 4.5 with iOS 5.1 and iOS 6.0 simulators installed.