Samsung Galaxy Ace S5830M CyanogenMod 7.2: Google Play gives error 492 after factory reset
This problem can be solved with the 492 Error fixer package from this thread here on XDA Developers. You just put it on the SD Card, reboot to ClockworkMod (which I'll assume you already know how to do), go to Install zip from sdcard, and install the fixer package.

Once you install it, you should be good to go.