Version 4.0 became final in July 2010. Products supporting the new spec should reach the market this year.

Foley predicts that the first crop of products incorporating the new spec will be "proximity-type devices." Such a product might be, for instance, "a key fob that will alert you if you accidentally leave your phone behind." As for other product classes, Foley expects "personal monitoring devices, like heart rate monitors, or personal fitness devices, like pedometers." He says that Bluetooth 4.0 will enhance home entertainment markets, too, along with security, automation, healthcare, and sports and fitness.

Right now, we're seeing plenty of new cell phones, headsets, and car speakerphones that support earlier Bluetooth specs--primarily Bluetooth version 2.1 + EDR (and to a lesser extent, version 2.0 + EDR). Earlier in 2010, Samsung rolled out its , one of the first phones to support Bluetooth 3.0, in Europe. (On the computer front, some PC makers, including , offer laptops with .)

All of the more recent Bluetooth versions are backward-compatible. So if your phone supports version 2.0 but the headset you choose supports 2.1, for example, the two devices will still work together; you just can't benefit from 2.1's enhancements (such as faster pairing), as both devices must support the newer spec for the added features to have effect. Conversely, be aware that, depending on your phone's operating system, you may not be able to take advantage of all the features that a particular headset or speakerphone unit promises. For instance, if your phone does not support automatic phone book transfers, you'll have to transfer your contacts' information manually via Bluetooth. Additionally, if you own a phone with Android version 2.1 or earlier, you will probably have trouble using some car kits' voice commands. And if your iPhone doesn't run iOS 3.0 or newer, you can't enjoy stereo A2DP Bluetooth support.