The ill-fated HP TouchPad has, ironically, proven itself to be a gem of a machine for those with a computing/hacking background – with a fast processor, plenty of memory, and the most open architecture of any tablet so far (in that webOS Doctor can be hacked to alter partition layout and contents on restore), there are few limits to what it could be used for. Android (hopefully within a webOS card) is coming, and already Ubuntu & Debian can be run from a chroot() environment. The ARM build of Gentoo can be run in the same way – but that’s relatively trivial and not especially interesting (in that it doesn’t integrate with the OS – you have to specifically enter the chroot() environment in order to make any use of the software).
I would now always choose to run Ubuntu in a desktop environment – Canonical have done a great job of generalising the historically painful job of getting hardware and software reliably working together (try getting Bluetooth HID devices and WPA Wifi working on Linux from first principals if you want a reminder of just how obtuse software can be…), but I’d still opt for Gentoo for a server/command-line environment. This is what we have with the TouchPad – a great visual OS, but a minimalist installed get of command-line tools. This – with it’s ability to build optimised, efficient, and light-weight packages with only the necessary optional features present – is where Gentoo shines.