Android Debug Bridge not just working on Mac?

For a while now I’ve been having an issue getting adb (On-Device Android Debugging) working on my Mac. I’d turn on USB Debugging on the device, plug it in (the notification bar told me USB debugging was active) but running “adb devices” does nothing. If you look at the Android docs they list instructions for both Linux and Windows, however “If you’re developing on Mac OS X, it just works. Skip this step.”
Well, the question is what do you do when it doesn’t “just work”? Ask Google, naturally. But the answer was elusive, so I thought I’d outline it here. Thanks to comments on Stack Overflow, it was pointed out that the app EasyTether sometimes causes issues. I vaguely remember installing this app but I could never get it to work and had uninstalled it ages ago. What I’d not realised is that since then, my mac thinks that’s what my HTC Desire Z “is” when i plug it in. So the first thing to do was to unload the kext file:

$ sudo kextunload /System/Library/Extensions/EasyTetherUSBEthernet.kext
# (type your password)

#and just to make sure it never bothers you again:
$ sudo rm -rf /System/Library/Extensions/EasyTetherUSBEthernet.kext
# (type your password)

Next was to go to System Preferences -> Network and to delete the “EasyTether” connection that still remained there.
Then unplug the device, plug it back in, and go back to the terminal:

$ cd android-sdk-mac_86/platform-tools
$ ./adb devices
List of devices attached
HT0BART00736 device

Job’s a good ‘un!