New Bluetooth cellphone headset from Sony Ericsson:

The new HBH-35 is a replacement for the popular HBH-30 and improves upon the device by getting a power boost. The new HBH-35 weighs the same as the older model, 28g, but sports up to 5 hours of talk time and 5 days of standby time - easily the best on the market, if the claims hold true.

Supposedly will work with any Bluetooth-enabled device that supports the Headset or Handsfree profiles. Which is great, since the lack of compatibility between headsets and phones of different companies has been a big headache for many users.
Read

[Gizmodo]