Dell Belize published an overview of the UltraSharp UP2414Q 24" 4K monitor. I must say, 3840×2160 in a 24" display would certainly look make text look "ultra sharp". The rest of the company still does not appear to be acknowledging its existence but I think this is a pretty safe rumor.
One of the selling points of Dell UltraSharp monitors is its color gamut. It is not too difficult to find a monitor with 100% sRGB coverage, but Adobe RGB is quite larger; the UP2414Q claims to be able to reproduce 99% of it. This means that, if properly calibrated, the monitor can reach "further colors" instead of approximating them. Specifically, 100% Adobe RGB is roughly the gamut possible with color printers.
Put into perspective: my Wacom Cintiq 22HD claims 72% coverage of Adobe RGB.
Image Credit: Wikipedia
Not much else is known about this display. It does not have a price. It does not have a release date. It does not even have an official announcement date. They do claim to calibrate the monitors before they leave the factory so that is some other information, I guess. It has four USB 3.0 ports and a 6-in-1 card reader.
But I can imagine the biggest omission for our audience is: there is no official announcement about refresh rates. Ian Cutress down at Anandtech assumes, based on the Dell UltraSharp 32" UP3214Q monitor, it will support 60Hz only using two DisplayPort 1.2a connectors in MST; otherwise, 4K will be limited to 30Hz.
I would be surprised if he is not correct.