Apple is currently signing old firmware read ASAP if you are stuck on 4.3.5
Over the past few minutes, the web and twitter have been buzzing with news that Apple has started signing 4.1 firmware and possibly even 4.2.1 firmware for some devices. This is amazing news for those who are currently stuck on 4.3.5 and up until now had thought that they would be stuck there until iOS5 came out.
Those of you who are stuck on 4.3.5 open up TinyUmbrella ASAP and try saving your SHSH keys from Apples server. So far there are varying opinions on what firmware is being signed and for which devices. Initially the report was that it was only 4.1 for the iPhone3Gs, but others have been reporting that even 4.2.1 is being signed for 3Gs right now.
Unfortunately for iPhone4 users, I have not heard of anyone being able to save their 4.1 or 4.2.1 SHSH on an i4 yet, but it's worth a shot!
We have no idea why Apple is doing this, possibly by mistake or maybe they are just trying to see if we are paying attention Either way, nobody knows how long this will last and it is VERY easy for them to stop signing firmware so do this AS SOON AS POSSIBLE!
If you try this and it does work for you, please let us know below, be sure to include what device you are using and what firmware you were able to save the SHSH for. Thanks!