One of the iPhone 4S features which was briefly mentioned during yesterdays Let’s Talk iPhone event was Bluetooth 4.0. Bluetooth 4.0 is a hybrid of current Bluetooth standards and Bluetooth Low Energy. It has many features that improve upon the current Bluetooth 3.0 standard which is widely used in current mobile phones. Apple has already introduced Bluetooth 4.0 into its latest MacBook Air and Mac mini lines.
Bluetooth 4.0 can offer a huge improvement in battery life as it consumes far less power than other Bluetooth versions when in Low Power mode. In fact, it is claimed that a Bluetooth 4.0 device can run for years on a standard coin-cell battery, it is that power efficient. Other features are low cost, multi-vendor interoperability, and enhanced range.
Low Power Mode is geared towards accessories with low power requirements such as in the health care markets; for thermometers, heart rate monitors blood pressure monitors etc. It could be that you will see a ton of accessories coming to the iPhone 4S to take advantage of this new technology. Of course for most, you will not notice any difference, your current Bluetooth accessories will continue to work in exactly the same way!
Source: Bluetooth SIG