To those who research this question in the future: The Switch ResX control panel, available as shareware, does a beautiful job at this. With the unregistered version, you can add one additional resolution to the standard set offered by Apple in the "monitors" control panel. If you use the Switch ResX control panel to define the resolution, then restart, you can select the new resoltuion. I had to then restart again for it the settings to work.
For those asking why, wherefore, etc:
The reason I want the monitor to be fed a 1080p signal is that 1080p is its native resolution; all flat panel/ fixed resoltuion displays look best at their native resolution. 1080i requires the display to re-create the progressive scan image, and is near-unreadable as a computer display.
Some might ask, why set to 1080p at all? Why not work in 720p, for example? The answer is that in general 720p is in fact better for me, biven the distance I sit from the display. However, for some applications like Garageband I need more desktop real estate not dedicated to toolbars, menus, etc. Finally I am curious to see how well the mini does at upscaling DVD content relative to the chip in my monitor.
As to whether it is possible via DVI, all I can tell you is that I did it yesterday evening and the display looked awesome. So I'm guessing it is possible.
The seems to be a lot of misunderstanding about the "demands" of 1080p out there. So far my experience has been that the Mini core duo handles the output of 1080p with aplomb, as do the cables, display, etc etc.
