I took a quick poke around an accessory store and found this:
HTC Wired Remote Control Stereo Headset for CellularSouth HTC Hero / HTC Hero, Magic / Sprint Hero / T-Mobile myTouch 3G, myTouch 3G Fender - Android Central Store
Seems there needs to be an add-on driver for it. Though comments left are unclear whether it actually does work for Android or not.
In either case, I think this is worth a bit more research. I listen to music using Etymotic ER-6i's via my iPod, while riding my motorcycle, and would love to have a fully integrated solution to work with the Evo. The Etymotic hf2's are close but would love to also be able to control music and such as these can.