New guidelines have been revealed for Bluetooth 4.0. You might be wondering where Bluetooth 3.0 was as it's not been seen on many or any devices I have come across. The reason for the lack of support for BT 3.0 was a problem with more speed requiring more power hence, phone manufacturers decided to stay with 2.1.
However, Bluetooth 4.0 aims to fix the concerns with 3.0 in that the new spec promises to do more for less... ie, higher transfer rates with less battery power needed.
The new Bluetooth 4.0 spec provides two modes which are single and dual mode. Dual mode is capable of switching between high speed and low power modes depending on what is needed at the time. The single mode is designed for ultra low power devices such as tagging systems and perhaps reporting systems in your car such as bluetooth tire pressure sensors.
If plans are successful then we should start seeing BT 4.0 devices showing up sometime in 2010.
Via: Everything USB