I was going thorough a lot threads and saw a lot people asking about working of gevey SIM on recently released iOS 5 and i thought i should write a complete post on "What you need to know about GEVEY SIM unlock and Ultrasn0w Unlock on iOS 5"

You should preserve your baseband while jailbreak no matter what

Mac Users can use redsn0w 0.9.9b5's new Custom IPSW option to create a Custom IPSW file with baseband preserved

Windows users can follow this guide to cook custom IPSW for their iOS 5 with base band preserved.

Ultrasn0w unlock aka Software unlock will be available tonight to unlock follownig basebands:
01.59.xx
04.26.xx
05.11.xx
05.12.xx
05.13.xx
06.15.xx (For 3GS users)

Gevey SIM will unlock following basebands:

02.10.xx
03.10.xx
04.10.xx
05.14.xx
05.15.xx
05.16.xx


i hope this solves your problem a little!

MODS Please make it a STICKY for couple of days
Cheers