Recently there are rumors abuzz about Microsoft's plans to add official Bluetooth 4.0 low-energy support to Windows Phone device with the 8.1 update that is due to roll out in 2014. The Bluetooth LE standard allows newer hardware to connect using less energy for transmission, saving battery and allowing continuous background syncing.
On the other hand Nokia updated the 520, 620, 625, and 720 with the 'Amber' update which brought with it support for Bluetooth 4.0. That update allowed the Adidas miCoach app to work with their heart rate monitor accessory. And now, Nokia has confirmed that the rest of its Windows Phone 8 devices will be getting the same support with the upcoming "Black" update.
The full support page answer reads, "Bluetooth LE allows you to connect your phone with special accessories like heart rate monitors. While doing that, thanks to Bluetooth LE connection, the accessory battery will last much longer, up to months.
It is already available for 520, 620, 625, and 720 with Amber. With Lumia Black software update, Bluetooth LE will be enabled across the full WP8 Lumia range."
The most important sentence is the last one, which says that Bluetooth LE will be enabled across the full WP8 Lumia range because, more health-related accessories or wearable technology (including smart watches) are the future trends which will rule the markets like phablets that are currently rolling out in the market.
Unfortunately, when it comes to the Black update, mentioned earleir, there is no word on when it will be roll out. All we know right now is that the Nokia Black software will be loaded on the Nokia Lumia 1520, but Nokia hasn't even announced the release date for that device yet. The Black update is expected to also include camera improvements, the new Glance feature, and many more.