I remember discussions about a kiosk, but I’ve never seen anything done.
I have a similar usage in mind, although bigger than a tablet. I live on a horse stable, my wife’s full-time business. I would like to build her a wiki to manage the farm: keep the lesson schedule, update the horses’ feeding instructions, track blacksmith and veterinary visits, log the work done by the horses, and more. I would love to hang a wireless touch-screen monitor in her office connected to some dedicated machine on our network that’s hosting TW on Node, with some automatic backups running.
The monitor would show a slideshow of horse pictures, but on touch would revert to showing a main view with the lesson schedule focused, and other read-only views easily accessible. (The lesson schedule will be the main reason for anyone outside the family to use the wiki.) There would be a keyboard also nearby, although perhaps not obvious. On some signal an edit interface would come up and she can update the daily tasks, or make other edits, all backed up in real-time to Node, and from there on some schedule to an SCM server. (So, I’m paranoid!)
I’m nowhere near starting this project, but a kiosk mode would be really helpful for me too.