Last week, MacRumors reader alansmallen noticed that Apple had discontinued their iPhone Bluetooth Headset, which had been released alongside the original iPhone in mid-2007.
At their recent iPhone OS 3.0 media event, Apple revealed that support for A2DP (stereo Bluetooth) will be included in the next-generation iPhone software. The iPhone 3G's hardware is capable of supporting A2DP, and upcoming iPhone models would of course also be expected to do so, but the original iPhone will be unable to support the technology.
Whether this means that Apple will be releasing a stereo Bluetooth headset or not remains to be seen, but it certainly seems to be a reasonable possibility.