I believe it will be keyed as well. Most (if not all) HTC USB ports are "proprietary" in the sense that they may make an accessory that will only work on their phones, but their phones are compatible with standard mini-USB connectors.
http://www.engadgetmobile.com/photos...h-pro/1029971/
Hey, could be worse! Imagine if Sony or Apple made the phone...
EDIT: Wait, I'm sorry... I didn't realize you were talking about the cable itself and not the port. My bad.
Are you talking about the included cable? Were you hoping to use it on other devices with standard USB ports?