Dell has released two new 4K monitors, and according to a story published by The Tech Report these are using IPS panels.
The new models are available on Dell's site priced starting at $599, which puts them into what had been TN territory just a few months ago. The original report came from TFT Central, which claimed to have leaked information about new 4K monitors from Dell with 60Hz IPS panels. Dell released the leaked model numbers at just $599 and $699 for the 24-inch and 27-inch versions, respectively.
Updated: Dell's website specifies that these are in fact IPS in the full tech specs rundown for each panel. I surmised that these could potentially be a VA or other panel type as well, as of course IPS is not the only display technology capable of wide viewing angles.
The monitors arrive factory-calibrated to 99% sRGB color (according to Dell's product pages) and feature tilt, swivel, and rotation, so they could be a great option where the full 178° viewing angle is preferred over the existing TN-based 4K offerings.