The Gadget: Maximo iP-HS2 iMetal Isolation Headset. It's a set of isolation headphones bundled with a mic so that you can seamlessly take incoming calls while listening to music. They are also silver so they'll match your phone/rims.
Verdict: Very buyable. Those with stock iPhone/iPod headphones will notice a major upgrade in sound quality. Deeper bass, fuller mids and an overall less muddled presentation of instrumentation make them a comparatively enjoyable listening experience, and the earpieces did a great job of blocking out airplane noise on a recent fight.
There's a multifunctional pause/skip/hang-up/answer button on the wire as well, and the package includes an extension cable and some extra eartips.
Taking a call with the headset was very easy (you hit the answer button on the wire or phone and the iPhone realizes that there's a mic plugged in). During our testing, we found the vocal quality was only a bit worse than on the iPhone's receiver, so really quite passable. The only weird part is that you might find yourself talking louder than normal since you are essentially wearing earplugs.
For those interested in a combination headphone/mic kit, you might also want to check out the highly rated V-Moda Vibe Duo headset. It runs about $20 more than this iMetal model, but the Duo offers a slightly better frequency response, too. [Maximo]
UPDATE: Maximo clarified that the headset is compatible with all iPhone versions without an adapter.