Yesterday Apple released the iOS 5 GM to developers. This is the final iOS 5 "beta" version to come out before the software's public launch, and in most cases the GM is identical to what gets publicly seeded.
In classic GM fashion, you don't actually have to be a registered developer to install the iOS 5 GM. That doesn't mean that it's not still discouraged, it just means that Apple doesn't check developer UDIDs when installing the iOS 5 GM...