I'd settle for a SIMulation. Not even of the later Palm os's, just the original Palm Pilot. Prolly wouldn't be hard to rip the look and feel, but Graffiti seems like it'd be a b*tch. Could a freeware project even use Graffiti without getting in deep doodoo?
Oh and don't the DS and the Newton have the same "type" of processor? Even if the Newton was somehow easier to do, I'd rather have a Pilot. Nice and simple... no overkill.
Plus, the Pilot had a Dragonball processor, and I loves me some Dragonball! Kameyameyameya baby!