I installed the app from Google Play and had nothing but trouble with it. It initially says that busybox isn't configured properly and that the init.d script is either missing or not installed. I proceed to configure busybox and install the init.d script, but after rebooting my "downloaded" apps disappear. These downloaded apps include the Google Play Store and mounts2sd! So even if I wanted to reverse the process, I can't because the app is gone.
I would appreciate if anyone could explain how to do this properly since there is very limited space on the Nexus One, especially after installing Jelly Bean on a custom HBOOT.