My friend works with ARM based chips with his work as an Electrical Engineer, he has told me a lot about those chips and I've sat and watched while he programs them. Mind you I have a fair amount (if outdated) of programing experience myself. Anyway, given all of that, the ARM chip is a ways away from doing the things that a 'super netbook' that you are thinking of. The great thing that a ARM chip has going for it is that it works with only 3~5 Hz of power. That is where the extended battery life is coming from. I'm not sure how much more a ARM chip can do without a serious die shrink. I think that the best chance of a super netbook happening right now revolves around the Intel Atom chip.
While a ARM based netbook might not be here in the near future, a ARM based sentry gun would totally kick @$$. No laptop computer would be required for something like that.
http://kotaku.com/5024636/some-guy-went-and-built-a-sentry-gun