I just happened upon something that I hadn't seen mentioned before: I've spent most of the morning backing up SHSH blobs with TinyUmbrella for all the iThings I'm responsible for (mostly iPT 2G and iPhone 3G and 3GS), to enable us to roll back their OS version in the future for regression testing and such. Lo and behold, for each of the 19 devices I've tried thus far, I've received blobs for every single 4.x release the device is capable of running. for the iPods, this is just 4.0, 4.1, 4.2.1. For the iPhones, I'm also getting 4.0.1 and 4.0.2, and surprisingly, 4.2b3. I've also successfully rolled several of these devices back to 4.0 or 4.1 using iTunes on a machine that does NOT have TU installed (or an edited hosts file), and that works as well. So I know without a doubt these SHSHs came from Apple, and not from Cydia. Not one of these devices has ever been jailbroken, and none have ever been hooked up to TU before. What they DO have in common is they're registered to our developer account. So it appears that Apple continues signing old OS versions for development devices, even after it closes the window for everyone else. I'll test this later today or tomorrow by registering my personal phone in the developer portal and seeing if I can retrieve the 4.0, 4.0.1 and 4.0.2 blobs for it. They're not currently available because my phone is a refurb replacement that I got with 4.1 in November. Any developers or people who begged/bribed a developer to add your device to their portal, give this a whirl and see if it works for you. Looks like there is hope for accidental upgraders/recent purchasers after all!