TinyUmbrella is a program for Mac OS X and Windows that allows us to save SHSHs and update to an iOS version without updating the baseband of our terminals. This update process with keeping the baseband only applies to iPhone 4 terminals and iPad 2 tablets, but you don't have to use it for iOS 5. The developer of the TinyUmbrella application announced on Twitter a few minutes ago that his program will not remove an iPhone 4 or an iPad 2 tablet from Recovery Mode after updating to iOS 5 and without a SHSH you will remain with the device locked in Recovery Mode.
Wait for TinyUmbrella to be updated and then you will be able to update without problems, but until this happens I recommend you not to venture.
