More details from analyst Shaw Wu's report about flash based Apple laptops indicate that he believes that Apple may deploy the iPhone's stripped down version of OS X on the rumored sub-notebook.
"The 'mini' Mac OS X will be used. In terms of software, our sources indicate that Apple is leaning towards using the same "mini" version of Mac OS X used in the upcoming iPhone. We believe this will be particularly important as it has a much smaller footprint and runs with as little as 4 GB of space."
Apple's iPhone is expected to launch June and incorporates a touch-interface. Apple has also been advertising for "Senior Panel Process Engineer" to design and develop advanced multi-touch panels. There has been no direct hints that Apple will use this in future laptops or displays, but Mac fans have certainly been speculating on this possibility.