R. Clayton Miller’s 10/GUI is an interesting look at what multi-touch desktop GUIs might look like. Obstacles are that it's difficult to position large desktop monitors so that one can comfortably touch-use them for extended periods of time; and that using hands to manipulate on-screen objects tends to obstruct the view to them. 10/GUI has two main ideas: First, to use a giant multi-touch track-pad. Second to rethink the window manager. The first idea makes perfect sense. The second idea is neat, but can probably still improved upon. The idea is still that an application should fill out most of the screen. Splitting a screen in half, vertically should work, but more than two partitions don't seem possible. My personal bet would be on 2.5-dimensional zooming user interfaces that restrict navigational movements (to improve usability). Fingers should work well to quickly organize files, documents, windows, etc. Bumptop solves this one aspect neatly. Windows 1, Eclipse, and Windows 7 have some intriguing ideas about how to split screen space between windows.
Interestingly, Apple's notebooks and their multi-touch trackpads are well positioned to implement something similar to 10/GUI. Already, multi-touch gestures for scrolling and zooming make some GUI widgets inefficient and unnecessary.
