While I like the idea of a multitouch PDA, I feel w/ the iPhone & iPod Touch, it might confuse many consumers.  I fear that someone would see an iPhone box and be like "Oh there's an iPod Touch" and buy that and later find out they were wrong b/c they didn't read.  I've seen countless people get frustrated about something and is easily solved if only they read the signs or whatever.
Also, people might get confused by the different offerings.  Not saying anybody reading this would get confused, but I know a lot of people who would spend a long time wondering which they needed.  It would be nice, imho, if they merged the iPhone & iPod touch.  The only thing that would need activation would be the phone part.  The music part, Safari, everything else would work w/o activation.
One thing I'd like to see is a 12" or so tablet Mac w/multitouch.  Full version of Mac OS X.  It would serve as a digital clipboard or something where someone can take notes on it w/ either their fingers or maybe a stylus.  Also, it could serve as a digital map.  I know at the zoo near me, they hand out paper maps and sometimes I get turned around.  It would have an accelerometer & maybe GPS tracking.  This way, you could have a "You are here" dot.  Plus if you turn to the left, it'll automattically adjust.  It would be good to have a stand, too or even better a base station.  The base station could have extra hard drives, optical drives and other expansion.
Two things that would be nice to be built in to the Mac OS X, iPod, & iPhone is better text-to-speech and better speech recognition.  Right now, text-to-speech is awful.  Sure, Leopard's going to add a higher quality voice, which I heard.  It still sounds awful and robotic.  For speech recognition, it would be nice to make a voice note & have it put into text.  This would really help w/ people who have a hard time typing/reading.  Or just someone who prefers dictating.  Just my 2 cents.