I am surprised no one has mentioned the Archos 5 tablet in this thread.

http://reviews.cnet.com/8301-12519_7-10353176-49.html

I am personally in the market for a similar device. The Maemo OS appeals to my Linux side more than Android, but the specs on the Archos 5 tablet are just so much better, and it is still Linux after all. I would like to hear what is on the pipeline from Nokia as far as a similar device. That may sway me into waiting a little bit. Otherwise, I think Archos is the current best alternative for this type of devices.