Yes everybody, this is true. It seems that Apple doesn’t want people to have the ability to downgrade anymore. This could be accidental or it could have been 100% intentional, either way, developers are in trouble.
Apple has stated that they “might” fix this in a later seed. Basically, what happened, was that they killed backwards compatibility with anything between 1.0 – 3.0 beta 2! This is a big issue for anyone that has updated to iPhone OS 3.0 beta 3.
Apple has also stated that you cannot develop any applications with 3.0 beta 3 for 2.2.1 consumption. Like I said, big issue here. Almost all developers are on 3.0 right now, so this could get a little ugly.
No one is exactly sure what Apple changed to kill off all compatibility with 3.0 beta 2 and under, but I do have some theories. I believe Apple must have reflashed the bootloader or something in the boot sequence (or DFU) which killed off backwards compatibility.
There is a baseband update in the firmware, but I know this is not the cause. I know this because iPod touch users are also subject to this issue of incompatibility with anything 3.0 beta 2 or below. As you all may know, the iPod touch has no baseband (because it really doesn’t need one, because it doesn’t make calls over the cell network).
So I will keep you all informed on this. So if you are on iPhone OS 3.0 beta 2, I suggest downgrading and abandoning the 3.0 beta ship until they get this resolved.