Mobile ODIN is the on-device firmware flasher of choice.

Just throw those firmware files on your (internal or external) SD card,
start Mobile ODIN and flash away.

Download:

Mobile ODIN FlashKernel v2.0 GT-S5570 (Mini)

http://www.mediafire.com/?b1tmbmpje3ny9lq

Mobile ODIN FlashKernel v2.0 GT-S5660 (Gio)

http://www.mediafire.com/?fagvexcrefqunpi

Mobile ODIN FlashKernel v2.0 GT-S5830 (Ace)

http://www.mediafire.com/?selt3i8krc49tsc

Mobile ODIN Pro v3.57

http://www.mediafire.com/?0xnc9iifmbjxu3w

Cara Flashing (One Package):

1. install kedua apk diatas

2. buka Mobile ODIN Lite

3. tap “Open file …”

4. pilih file firmwarenya ( .tar / .tar.md5 )

5. tap “Flash Firmware”

6. tunggu sampai proses slesai

NOTE:

Jangan coba upgrade dari froyo ke GB atau sebaliknya dgn app ini

USE AT YOUR OWN RISK!

Mobile ODIN Thread

http://forum.xda-developers.com/showthread.php?t=1347899