K So I sat down and read the whole thread instead of just the last two pages.

to the guy that said he jailbroke his iphone and bricked it.... I think you mean it got stuck and you restored it because you didn't know how to fix it. Bricking something means that it is just that... A brick, it can't be fixed. By deffinition iphones are unbrickable because of the restore option. Not trying to be rude, just pointing out a fact.

What Jailbreaking/Unlocking does :

Jailbreaking an Iphone allows it to run on T-mobile... At&t and t-mobile have a similar baseband. when you jailbreak the iphone it allows it to be used on t-mobiles network. =P

Unlocking an Iphone allows you to use 3rd party apps. There are a TON of apps and modifications that can be done to the iphone through the cydia network. Basically cydia is itunes with out Steves psyco controlfreak rules (also no music). Cydia apps have tons of stuff! Inculding things to change the background of your iphone, your fonts, springboard res, tethering, multi-tasking. Heck theres even a beta flash out there.