Close I suppose. Yellowsn0w is an unlock for 2.28 baseband on the iPhone 3G, redsn0w jailbreaks the iPhone/iPhone 3G and unlocks the iPhone and ultrasn0w will (eventually) unlock 4.26 (OS 3.0) baseband on the iPhone 3G.
Please remember, jailbreak != unlock and vice versa, although you need to jailbreak TO unlock.
Close I suppose. Yellowsn0w is an unlock for 2.28 baseband on the iPhone 3G, redsn0w jailbreaks the iPhone/iPhone 3G and unlocks the iPhone and ultrasn0w will (eventually) unlock 4.26 (OS 3.0) baseband on the iPhone 3G.
Please remember, jailbreak != unlock and vice versa, although you need to jailbreak TO unlock.