Heres another Android 2.3.3 Gingerbrd firmware version update for Galaxy Gio S5660 with build S5660XXKPK. This is recently an official update from KIES server for Europe version of Galaxy Gio. So, users from other regions from Europe can get an update via KIES.
There are three version of S5660XXKPK stock ROMs now available, and can be used to manually