Thanks. I knew they included Bluetooth 4.0, but Low Energy was left out of the specs page. I actually still can't find any mention of it except in CoreBluetooth - their site organization is a bit painful if you're not there to buy.
There's also a demo implementation for Android by one of the radio manufacturers - not great, but maybe usable for initial development. This is much more significant on iPhone because it diffuses into the market more rapidly than a single model of Android handheld usually will.
Not sure this is what you meant, but the iPhone 4S already has a Bluetooth Low Energy radio and an API to control it (CoreBluetooth).