Given the trouble ASUS had getting their Eee Keyboard onto the market, we're not really surprised that Apple aren't planning an all-in-one PC and peripheral combo themselves. Still, Steve Jobs' omission is a gap for a modder, and over at the MacBook Air Project Bart Reardon has taken it on himself to craft a custom keyboard PC based on the guts of a first-gen MacBook Air, an Apple keyboard and a new Magic Trackpad.
As you might expect, the Apple peripherals are simply too skinny for even the Air's slender motherboard to fit inside, so instead a transparent plastic tray has been crafted. That contains the Air's guts, and the keyboard and trackpad sit on top; they're generally unmodified, so that they can be used with other (more powerful) systems.
Originally the undertray was scaled for an older Apple keyboard, so it's now undergoing some shortening and the port holes are being cut to suit. When finished, the keyboard-Mac will likely be put into play as an Apple TV replacement, just as ASUS expect their Eee Keyboard to be used.