Apple's proprietary Apple Display Connector (ADC) may not be quite so proprietary or such a smart piece of Apple technology as the company would have us believe.
According to one Register reader, ADC is simply is Plug and Display (P&D) port, developed by the Video Electronics Standards Association (VESA) under the sponsorship of IBM and published as a standard in June 1997.
And, indeed, Apple's ADC port does look broadly like a P&D connector.
P&D transfers both digital and analog video data to a compliant monitor. It also provides a USB channel and an optional IEEE-1394 (aka FireWire) channel too - which is exactly what ADC does.
P&D is not dissimilar to the Digital Visual Interface (DVI) connector, though the latter omits the USB and FireWire lines. Given the greater support for DVI in the digital display world, it seems likely that ADC is, in fact, a version of it with the USB lines enabled.
In that respect, ADC would be proprietary. The connector at the Mac end could also support standard DVI screens - they'd simply not provide USB throughput.
Apple's monitor tech specs. don't describe the true nature of ADC, so it's difficult to say how accurate our reader's claim is. However, the ADC port looks pretty much like a P&D or DVI port, so there's got to be something in it.
Apple's monitor FAQ states that its new displays were designed specifically for the new Power Mac G4 and the Cube, but that's not an explicit statement that you can't use them on a Windows machine equipped with a suitable display card. The tech specs. for, say, the Cube only lists Apple's monitors and standard SVGA screens as compatible.
Perhaps someone from Apple would like to set the record straight? ®