How can I clear the cache(s) of my g2x from adb?
I am not sure about the G2X, but when I would reboot in to recovery on my Galaxy S Vibrant, I used to have to "apply updates", which would run the update.zip that was on the sdcard, this would bring me in to the clockwork recovery. 

I also know that the adb reboot recovery does not yet work correctly on the Galaxy S Vibrant version, so this could be the same issue on the G2X.