I haven't yet seen anyone clarify the "iPhone runs OS X" statement seen in the keynote and online.
Is this something like "OS X Mobile" or are they claiming it's the full-blown OS? I can't imagine that we'd genuinely be able to install any old OS X app on the iPhone. I know Jobs hyped "desktop-class applications" on the device, but that's different than saying, for example, "you can install iWork '07 on the iPhone."
Color me AMAZED if I'm wrong, but I think this is more like a new PDA OS from Apple, even if it's built on BSD with many of the core technologies from OS X ... which is still unbelievably great news for Mac fans.
I like the Mac phone/PDA combo. Why? iSync. Apple has developed a tremendously stable, integrated syncing system on the backs of other mobile device manufacturers.
I can't believe that iSync, a major component of Tiger, was developed solely as a framework for letting users sync with devices from OTHER manufacturers. I suspect all we've seen so far is really an "advanced beta" of iSync in preparation for the real intent: syncing seamlessly with an Apple-branded device or two.
As for the specific phone/PDA combo, I can't see Apple making a standalone PDA in today's market. I'd buy it, but I can't see it happening. A mobile phone, on the other hand, would have to at LEAST be "smart" enough to handle iTunes transfers and iSync handling of Address Book and iCal info.
If they're going a step further with the phone and developing their own OS, rather than using an existing OS (which I think would be a given) there's very little reason to NOT make it a "full" smartphone running some new "Mac OS Mobile."
What Do You Think of the iPhone?
Predicting MacWorld by Looking Backwards