I have seen many tablets running Ubuntu 11.04. It is touch screen friendly
and should work fine with any flavour from Canonical. I don't own a tablet
so can't say I've done it myself. But I watch these things closely because I
want a tablet. :)

See:
androidadvices.com/.../
http://www.youtube.com/watch?v=xDB0PMrGdN0
thexoomtablet.info/motorola-xoom-now-running-ubuntu
thetechjournal.com/.../...-on-the-nook-color.xhtml