there is no jailbreak for 4.0.2 unless im out of date, but as far as i know you need 4.1 to jailbreak. with that being said you need jailbreak in order for an unlock
No. You can jailbreak 4.0.2. I did it yesterday. Then I updated to 4.1 and had a few problems. But today i've unlocked a iphone 4 with 4.02 that i brought in L.A and now have a iphone 4 with 4.1 in London, England.