I voted for beefed-up iPhone OS X...
But, as I've posted elsewhere, it's almost a meaningless differentiation.
Apple has evolved OS X (and the SDK) so it is modular, portable and [relatively] platform independent.
Apple can package various components together to run a variant of OS X tailored to a specific device type, be it an iPod, AppleTV, iPhone, tablet, game console (or other future devices).
consider:
--Most iPhone (Cocoa Touch) apps can be made to run on Mac OS X (Intel) through the iPhone Simulator. You can pinch/zoom with the kb and mouse.
--Some components developed for a specific device, can be generalized/modularized to run on other devices, and become a component of the total OS X. GPS / Location Services is a good example. Developed for the iPhone, it can be useful for laptops.
--Cocoa Pen (or somesuch) could be developed for a tablet [OS X Variant], then added to the general OS X components, to provide that capability to desktops and laptops.
--Draw, Paint, Hand Printing Recognition, Handwriting Recognition could be developed for devices where they make sense based on either Cocoa Touch, Cocoa Pen or both,
Since the NeXT days, the OS has been enhanced, evolved, modularized, re-factored, and ported to run on:
-- Motorola 68000
-- Intel
-- PPC
-- ARM
-- maybe other CPUs like Cell, PASC
So, the CPU need not be the determining factor in which OS X variant runs on a device.
What goes into the OS X for a specific device should be determined by the needs and capabilities of the device and its probable uses, more simply "what makes sense":
-- multiple windows or multiple-column tables (ala Mac OS X) don't really make sense on a 3.5" [iPhone] display, but they would on a 6", 10" or larger tablet.
-- A touch or pen UI may not make sense on an iMac's display, but it would make sense with a horizontal accessory tablet display used for painting, drawing or as a light table or studio controller panel.
-- Location Services would not make sense for a fixed-location iMac, PowerMac, or AppleTV. But it does for many mobile devices.
-- Pen or Stylus input doesn't make sense on a mobile phone, but it does on a tablet.
The point of all this is that Apple already has an OS, OS X that can do all this, and it can be packaged (customized) to exploit the needs of a marketplace [device] with the greatest efficiency and utility.
Not: real soon now; later this fall; early 2010; end of 2010... but Now!
"It's the User Experience, stupid"
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