You know, I've done a bit of thinking about this and I'm not sure what one would change about Mac OS X to "merge" it with iPhone OS.
The kernel level stuff is already quite shared between the platforms. That'll continue to evolve.
The apparent user interface doesn't seem to me too likely to be merged: "computer" (I'm not including "iDevices" in this usage) tasks are much more suited to having multiple overlapping windows - I don't see multiple overlapping windows being removed from Mac OS nor added to iPhone OS. Likewise, computer apps are designed around a keyboard/pointing device paradigm, which doesn't seem likely to change... I wouldn't be at all shocked to see some more touch capabilities come to Macs, but I don't see them becoming primarily touch-based... anybody that has used iPad's Numbers app or done a lot of text cutting/pasting on an iDevice knows that heavy usage of these types of functions are more suited to a mouse/keyboard than touch. And it's just less comfortable when sitting at a desk to have to reach out and touch a several-feet-away screen.
And, while many do, I don't see the unrestricted Macs vs restricted-to-the-App Store iDevices split going away... I just can't imagine how to make a successful computer that has such restrictions on it. Could be wrong here of course.
So what does that leave? Lots of the APIs are already quite similar, but there's of course room for more unification there: AppKit isn't as nice as UIKit in a lot of ways. But that doesn't seem too exciting.
Full disclosure: I'm one who shunned the idea of touch as a primary means of interface, but these days I use my iPhone and iPad far more than my Mac. So take everything I say with a grain of salt. :)
The kernel level stuff is already quite shared between the platforms. That'll continue to evolve.
The apparent user interface doesn't seem to me too likely to be merged: "computer" (I'm not including "iDevices" in this usage) tasks are much more suited to having multiple overlapping windows - I don't see multiple overlapping windows being removed from Mac OS nor added to iPhone OS. Likewise, computer apps are designed around a keyboard/pointing device paradigm, which doesn't seem likely to change... I wouldn't be at all shocked to see some more touch capabilities come to Macs, but I don't see them becoming primarily touch-based... anybody that has used iPad's Numbers app or done a lot of text cutting/pasting on an iDevice knows that heavy usage of these types of functions are more suited to a mouse/keyboard than touch. And it's just less comfortable when sitting at a desk to have to reach out and touch a several-feet-away screen.
And, while many do, I don't see the unrestricted Macs vs restricted-to-the-App Store iDevices split going away... I just can't imagine how to make a successful computer that has such restrictions on it. Could be wrong here of course.
So what does that leave? Lots of the APIs are already quite similar, but there's of course room for more unification there: AppKit isn't as nice as UIKit in a lot of ways. But that doesn't seem too exciting.
Full disclosure: I'm one who shunned the idea of touch as a primary means of interface, but these days I use my iPhone and iPad far more than my Mac. So take everything I say with a grain of salt. :)