iPhone 4S comes with full support of Bluetooth 4.0, which means it can work in "low energy" mode. As far as I know it's a completely different protocol on the physical level, but on the application level in many ways similar to the classic BT.
My question is, are there separate radio units for BT and BLE, i.e. can iPhone 4S use both channels simultaneously? For example, can you connect an audio device via BT classic and some low energy heart rate monitor at the same time?