These custom IPSWs can update your main firmware without updating your baseband (which would kill the yellowsn0w injection exploit).
Most people with a jailbroken i Phone will end up with a "factory-fresh" i Phone after the 1.1.1 firmware update.The guide is applicable for Upgrading i Phone 2G/3G 2.2 or 2.2.1 to OS 3.0 and also for i Pod Touch. Sandip Dedhia is the founder of Blogsdna.com, he loves to write on technology, gadgets & web services.Please note in order to upgrade i Phone to firmware 3.0 you must have installed i Tunes 8.2. At Blogsdna you can read his Windows tutorials, free and useful software related articles.Apparently the security is going to be a whole lot harder to crack this time around.As for unlocked i Phones, you should probably hold off for the time being.But since the latest firmware updates i Phone 3G's baseband to , you will not be able to unlock it.You will need to wait for some time for the Dev team can unlock baseband .So for i Phone 2G owners who care only about keeping their unlock — not about jailbreaking — you can take this update right now.If you haven't already bitten the bullet and taken your unlocked i Phone down that scariest of paths, the 1.1.1 update, we're here to sort out a bit of the hearsay from the actual and fairly inconvenient truth.Few hours are left for final OS 3.0 release and good news about i Phone jailbreakers & unlockers is that i Phone Dev team is ready with Quick PWN & Pwnagetool to jailbreaking i Phone Firmware 3.0 also new unlock Tool ultrasn0w is getting ready under i Phone Dev Team roof. Do not disconnect your i Phone until the update has finished That’s it, Once update is finished your will have i Phone 3G running latest firmware 3.0.Here is simple guide for those Users who will be first time upgrading their i Phone 2.2 or 2.2.1 to firmware 3.0. Select your i Phone under Devices in the Source List on the left. In the i Phone Summary pane, click Check for Update. Upgrade to firmware 3.0 is free for i Phone 2G /3G users however i Pot Touch users need to pay to upgrade to OS 3.0 Please Note: Above guide is for those users who do not intend to unlock or jailbreak their i Phone’s.