Interesting... that tells me that there absolutely is some kind of passive sensor embedded in the car dock plastic itself. Because if I understand correctly, the car dock does not ship with any power source. So if the Atrix "knows" when it is in a car dock, that means there probably is some kind of magnet embedded in the plastic of the car dock.
Could be NFC stuff though, but I doubt it.
will try the anycut thing later.
Thanks
Edit: Feel like doing a nerd a favor? If you have any strong magnets around, put a strong magnet near your dock when you insert the atrix. If the dock sensor is magnetically based, that should "jam" it by having a much stronger field. Tell me if it still detects the dock.