Firmware update iPhone?

For 3G jailbreak normal a long time ago. Literally Monday through 4.2.1 on the 3G and did the jailbreak. Unlock did, because the Russian machine. For a locked ultrasn0w is in cydia.
Problems with the unlock iPhone4 only. 3Gs unlock is only for baseband 06.15.00. Well, the jailbreak for iPad/iPhone4 is only bound (or rather unbound and there, but a beta version with bugs)

Under iOS 4 3G old ugly works.

My advice, either don't update or wait to normal jailbreaking 4.2.1. But in General no sense to put 3G on 4 OSes, not much. Is that because of the new toys, but do understand that 3G is already too soft for most of them.

Gail is critical?
Unlock need?
If not then just update today, tomorrow, Gail will be. If American, then we have to wait.

I have firmware 4.2 on your iPhone 3G, noticeable enough brakes as operatsionka and applications. Better leave it as is if a new firmware for you is not critical.

In short, the latest 4.2.1 firmware. Jailbreak is possible only if you have a Mac (meaning untethered), and beta flasher is very unstable.
\r
My advice — put 4.1, it does not differ from 4.2.1 in addition to air services, which I am more than sure you don't need.
\r
If you update to 4.2.1 unable to say goodbye to Gail in principle.
Before you update to 4.1 make sure to save SHSH BLOB in Cydia!
\r
Tethered jailbreak I do not see at all.