Does Google's new Android Market website ignore custom ROMs?

Now that the Android Market website has finally launched (and stabilized) we're beginning to see reports of rooted devices, and some running custom ROMs, not being recognized by the website. We're having the very same issue ourselves, where a pristine Desire Z running a factory installed copy of Android 2.2 Froyo is listed on the "My Device" page while an old HTC Hero hacked to run Froyo courtesy of FroydVillain ROM does not, even though it's logged in and syncing using the same Google login ID and the Android Market has been recently used from the device (as Google recommends on the "Trouble Downloading" help page). So what about you oh reader, oh rooter... what are you experiencing?
[Thanks, Florian]