I’d suggest that Apple’s proposed tablet will leverage the App store by being iPhone-app-compatible and the Mac OS X ecosystem by actually being a Mac, except with no keyboard. It will serve the role of a laptop by virtue of supporting bluetooth keyboards, and I suggest that Apple sell one or more keyboards that “clip” onto the gadget turning it into a more conventional notebook when that’s required.
The “lid” I’m proposing could be a conventional keyboard and trackpad combination with a clip or stand for the display, or it could be a hybrid trackpad/soft keyboard (e.g. essentially a tablet with a keyboard printed on it). Or they could do both. Or they could simply publish a spec and leave it to third parties. Apple could also let one TouchBook pair with another, turning one into a soft keyboard of sorts.
It follows that you can use your TouchBook — let’s say — as a giant iPod Touch/iPhone/touchscreen Mac while out and about, then simply prop it up on a stand (which doubles as a charger and dock) and use it with a bluetooth keyboard and mouse or trackpad or hybrid tablet combination as a mini desktop. It might even drive an external HDMI monitor (or, alternatively, it might retain mini-DVI but actually offer a cheap mini-DVI-to-HDMI converter).