Really sad to see that the tablet pc has been shoved into the ugly market that Apple so uselessly gave us. Well, not that they were ever really a prominent contender in the computing scene... Sure, at least Asus and some other companies are making windows based tablet PCs (though, WAY more pricey than the little 'pad' tablets flooding the market), but most of the stuff you see coming out nowadays are just huge smartphones without the phone aspect. If you want something that you can actually do some legitimate artwork on, you might look into some
older tablet hardware that pops up on eBay a lot that run windows and, consequently, any application within its hardware capabilities that you could run on any other windows machine. Or put linux on it, whatever you like. But with the android tablets and iPads all you will get is a glorified store and a slew of apps. At the mercy of app developers, so I guess it's just hoping that somebody out there is making some full-featured bitmap editing app software that it's just a toy.
But you never know. Even the Nintendo DSi was graced with some decent homebrew applications that people made, and the surprisingly capable dsiware title
"Inchworm Animation" that lets you do stop animation with the onboard cameras, tile creation, painting with aliased/transparent brushes, layers, and even has pixel art friendly toolsets and tops it all off by giving you the ability to export things you've made into SWF files or bitmap frames to an SD card.