Maybe someday I'll get a tablet, but for now PPC does everything I need and more, no reason to spend good money on something I don't need. And I like the keyboard/mouse(touchpad) interface much better; touchscreens are nice for navigating and whatnot I suppose, but they can become a bit cumbersome after a while, and don't even get me started on how much I despise virtual keyboards.
People buy tablets to mess around on the web and play games, and that's perfectly understandable. (I actually wouldn't mind having an HP Touchpad if I could, just to see what's supposedly so much better about tablets) I personally really only do light web browsing, maybe some medium-sized file downloading tops. Heck, I'm making this very post from a clamshell iBook running OS 9, there really isn't much I need power for. 😉
But, I can't say I would recommend a PPC for someone needing to do YT/Flash based sites. It'll work, but probably not to their satisfaction, whereas I and many of us know the limitations these machines have and make do. Tablets are the future I suppose, but it's nice that PPC is still around and still very useful if you lower your standards slightly and know how to use them.