i haven't tried to root 2.2 yet (i've just used the 2.1 and move to xbin method so far)
i hear the 2.2 method can take a few tries. maybe try it again and see.
the easiest way to check is to run an app that needs root and see if the ninja's permission window pops up.
that or in adb shell run a "su" command and see if the prompt changes (make sure you allow it on the phone, it'll ask after you use su.)