I don't have a BackFlip, but do write Android apps and use ADB regularly. So figure'd I throw this out there for Mac/Linux people:
On MacOS, ADB doesn't need a USB driver for your phone. Just download the SDK, and you can execute ADB from a terminal.
On Linux, all you need to do are to follow the instructions here:
Developing on a Device | Android Developers
Specifically the bit about creating and chmod'ing an /etc/udev/rules.d/51-android.rules file.
Hope AT&T fixes this issue soon, it's ridiculously stupid to attempt to disallow non-market apps given that ADB works.