With all of the touch devices to come out of Apple recently such as the Magic Trackpad, iPhone, iPad, and iPod Touch, it only makes sense to bring that touch functionality to the desktop market. Patently Apple found this European patent that shows the familiar form of the iMac, however with an adjustable stand and apparently touch screen capability. There is also evidence of an accelerometer, which might be used to change the interface into a touch based one that is akin to the look of iOS.
New York Times blogger Nick Bilton wrote earlier this year about how engineers from Apple told him that they were working on simplified touch interfaces like iOS however for a desktop. Please note that iOS would not overtake Mac OS X, it would just work on a layer above it, somewhat like Front Row.
Simplified touch interface shown in patent.
For the applications that may work better in a touch situation, these computers will have that new functionality. If there are other applications that work better with a keyboard and mouse, then you will be able to use them in standard mode as well. This is all adding features to what you have, iOS isn"t replacing OS X, but enhancing it for greater capabilities.
The company"s patent also shows a MacBook that could be transformed into a tablet which would switch the interface from the current desktop experience to an iOS interface when in tablet mode. Apple"s MacBook tablet patent would also be an ideal device for schooling as the smooth transitions from OS X to iOS could allow for hand written notes (think math class) and traditional typing for lecture based studies.
Image Source patentlyapple.com