I agree about mobile vs portable. A lot of folks like the 7" Tablets because they are easier to tote around and try to stash in a big pocket, but still big enough to easily see the screen for most people. I just got my second cheap Tablet at Big Lots here in the states because it has a capacitive screen, 1ghz cpu, plays angry birds nicely, and has HD video out for 99 bucks. I do sometimes watch my HD video captures on it, watch Youtube videos, check my mail, and surf a bit. It has WiFi only of course but I have that here and it works very well too.
I can see tech savvy families using them as mini TV's and driving up bandwidth use easily.
I also have a 4.3" PMP player that can do HD video and output to a TV in 720p. Now that is a mobile device and the screen looks great being so small but high quality, it just doesn't do what my bigger tablet can now.