"This upcoming version of PwnageTool will be based on Geohotís Limera1n bootrom exploit. It will allow you to jailbreak your iPhone on iOS 4.1 with a custom firmware that wonít change your phoneís baseband. This will, consequently, allow you to use Ultrasn0w to unlock the phone and use it with a carrier of your choice."
PwnageTool 4.1 for iOS 4.1 on iPhone 4 Jailbreak, Apple TV 2G Releasing this Sunday | Redmond Pie
does this mean that anyone with prior 4.1 version just need to run PwnageTool and the OS will upgrade retaining baseband for unlock with Ultrasn0w?