We've seen the Meridian 810 Reference Video System before; it's the first 4K x 2K video projector available to the consumer. It won't come cheap a just a few thou south of $190,000 for the projector, video processor (needed to scale available 1920x1080 material up to 4800 x 2400. It looked fabulous, even though even better images are possible from it with native 4K program material (essentially non-existent to you and me). They had to settle for a 10' wide projection screen (a curved, 2.35:1, Stewart Studiotek 130), and were claiming 48 foot-Lamberts! Clearly the projector is intended for a much larger screen.
The 4K chip (from JVC) must be fed from four separate DVI inputs, each one carrying one-quarter of the signal (a single DVI cable cannot carry this high a resolution).