TouchPad 4G, Go, and Go 3G available for HP product registration, should you happen to have one
Got an HP TouchPad 4G, TouchPad Go, or TouchPad Go 3G and want to make sure HP both knows about it so they can send you product support alerts for the product that was never released? Well, you're in luck - HP's product registration page actually has options for the aforementioned unreleased webOS tablets. If you do a search for TouchPad it spits out four options, only one of which was ever actually released. Other options include registering your TouchPad Bluetooth keyboard and slipcase, should you feel the need to receive support alerts for a sleeve case. Granted, we doubt HP's system would actually recognize the serial numbers of any TouchPad 4G or Go [addendum: AndrewRich in the comments notes that the system accepted his TouchPad 4G serial number, but it's possible the system doesn't actually reference a database for valid serial numbers] , but the fact that they're listed in the registration system is an indication that they were relatively close to launch before HP pulled the plug on webOS hardware.
Source: HP Product Registration (search TouchPad); Thanks to EvanKr for the tip!