1600x1200 is sort of a soft limit given the current crop TMDS transmitters (165MHz). That's probably the source of your "limit" comment. However, by using reduced timing intervals, it's possible to push 1920x1200 from current hardware. We do this by reducing the blanking interval for Apple's current Cinema HD.

However, to surpass this resolution we would need a new crop of hardware. So panel manufacturers (some high end ones like Eizo, Totoku and IDTech) are now using dual-input displays (IDTech's 22" display actually taks 1, 2 or 4 inputs). Either dual-link or genlock (or other syncronizing method) to get multiple digital outputs feeding portions of the display. I have this running on 3MP (2048x1536) as well as 9MP (3840x2400) displays. 3MP at 60Hz and 9MP at 24-30Hz depending on config.

Incidentally, current ROM revisions for our Mac cards support DVI Hotplug right now - plug in a display and it will instantly come online. This allows you to switch displays live or add a second display live. No user intervention is needed in the OS. If you don't mind manually selecting a menu item, then you can also make a VGA or TV connection live. Just another interesting item. That Dell article is a nice primer. It makes a few bold statements about what is currently supported by the industry however. No all display adapters conform to the full feature set available - hot-plug for instance. I can tel you right now that there is no display adapter in th consumer space for Windows or Mac OS outside ours that offers the level of display suport and special features we have. Stay tuned for our new control panel for Mac OS X (partially designed by yours truly )

Bruno