I'm going to say Powermacs can use any PC VGA or DVI monitor (commercial). A PC cannot use a Mac Cinematic Display without ~$500 worth of adapters. Because Mac Monitors use a cable that combines DVI, Power and USB into one cable. And I don't think the ADC-VGA adapters will allow the PC to use the Cinematic Display's USB ports.
BTW, Powermacs come with a DVI - VGA adapter.