Sony's 4K Ultra Short Throw projector is coming to Europe next summer. No pricing yet (it won't be cheap) but it'll let you turn a blank wall into a giant UHD display, surely worrying cinema owners everywhere.
Mounting projectors near the ceiling of a conference room keeps them out of the way, but it also means you're almost completely dependent on a remote if you need to tweak any settings. If it goes missing, it's time to find a ladder. Or, switch to Epson's new EB-595WT short-throw projector which features built-in touchscreen functionality that works on the projected image.