Clearly resolution independent windowing & UI widgets are also a prerequisite, and as this would likely require most existing applications to be extensively modified I don't see either Apple or Microsoft rushing to get it done.
According to a Wikipedia article[1] Microsoft did a good job when it comes to resolution independence, and Apple also makes progress on that front.
"Microsoft Windows has supported DPI aware programs since Windows Vista and allows user specified DPI settings for the windowing interface. [...] The Windows Presentation Foundation from Microsoft, and consequently, WPF applications, are also designed to be resolution-independent."
"Apple has included some support for resolution independence in recent versions of Mac OS X, which can be demonstrated with the developer tools Quartz Debug, which includes a feature which allows the user to scale the interface."
