unlocked 3gs

[bova80]

so once you unlock the phone is it unlocked for good or if you do a restore is it locked again?

 

[Fast/Furious]

What firmware do you have currently / which firmware do you plan to restore with?

 

[Applejuiced]

so once you unlock the phone is it unlocked for good or if you do a restore is it locked again?

When you software unlock any iphone by Jailbreaking and unlocking it will always lock again to its official carrier if you restore or update it to official carrier.
You should never update a JB and unlocked iphone unless you know what you're doing or else you'd be stuck with no unlock and maybe no JB options.

 

[bova80]

What firmware do you have currently / which firmware do you plan to restore with?

I'm running ios4 with it jailbroke and unlocked. Tested it on tmobile and it worked great.

 

[pixelated]

A software unlock, e.g. ultrasn0w is lost when you restore.
A factory unlock, set by the official network provider, stays when you restore