I just ported Android 4.2 from Acer A500 to A200. Thanks to our good friend: randomblame (AOSP 4.2 - Jellytime early build available - V3 - xda-developers)
ROM is very unstable atm.
How to install:
If you're are on cm10/9 you don't have to wipe anything, If you're using an other rom which isn't based on 4.x.x you have to do a data/factory reset.
PLEASE GIVE ALL THE CREDITS TO RANDOMBLAME, he's awesome!