Is the iron loan clipped to your ear too much to bear? Are you a sucker for anything crafted from carbon fibre? Blutrek's Carbon earpiece might draw you in, weighing only a scant 7g, with Bluetooth 3.0 support.
Personally, in the rare few times I've ever used a Bluetooth headset, weight hasn't really been an issue, but if you're the sort who walks around all day with one clipped on, your ear might thank you for something a bit more feathery - though it'll run you $US70. [Blutrek via Engadget]