Plantronics Voyager PRO+ Bluetooth Headset

Pros: Comfort (even though it is big).
Noise/wind reduction is excellent (better than Blueant Q2 or Jawbone Icone/ERA).
A2DP streaming.

Cons: Look is professional but boring. Design needs to be updated to a more modern appearance.
No caller ID announce (name or number).

Summary: I have used just about every headset on the market, and this is one of the best.

For those users that are experiencing issues with notifications and the iPhone 4, please be aware that this is not a defect with the headset. This problem will occur with any A2DP equipped headset (Blueant Q2, Jawbone, etc). Apple has designed their device to route all sounds through the headset and not the handset with A2DP enabled. The only exception to this is the ringer. Hopefully Apple will give us the option to customize this configuration with a future firmware update (i.e. ability to route sounds through headset and handset simultaneously, or just handset or headset, etc.).

For now, the only solution is to jailbreak the phone and install BTPS (bluetooth profile selector). This will enable you to turn off A2DP, which will route sounds through the handset.

Updated on Jul 5, 2011

Update: BTPS will no longer work with IOS firmware 4.3 and above. http://blog.ramondeklein.nl/index.php/2009/10/04/btps/

As of now, there is no way to turn off A2DP on the iPhone unless the headset supports the feature. See the Jawbone ERA if you need to turn off A2DP.