Looking for a micro USB audio/power hybrid

[csampson4]

Similar to this:

SiK, Inc. :: imp

So that I can just have one thing to plug into my phone while in the car.

I've seen this:

HTC Multifunction Audio Adapter for Dell Aero / HTC Hero (Unlocked), Hero, Droid Eris / T-Mobile myTouch Fender, T-Mobile myTouch 3G - Android Audio Adapters - Phandroid Store

But apparently it doesn't work for Thunderbolt? Which seems weird. Anybody seen something like this or know if the HTC one is actually compatible?

Thanks!