I got the Samsung U28D590D working at 4k with a SP3 i7, but it was not very easy. I could not make it work with a single mini-DP to DP cable, I had to interpose a mini-DP to DP/HDMI converter box (I used an inexpensive monoprice one) and then the connection ran: sp3 => mini-DP cable => monoprice converter => DP cable =>Samsung. I installed the 3960 drivers, you need to download the drivers, unzip them, then control panel, device manager, display adapter, upgrade driver, browse my computer, [key step:] "let me pick a list of device drivers", select intel 5000, then "have disk", windows will prompt you to insert a floppy disk into the A: drive, then browse to where the drivers are unzipped and select the .inf file.
After that it was a couple of reboots, and managing and setting resolutions for the two displays. Windows has the stupid arrangement where the windows built-in display manger appears to cover pretty much the same functions as the custom intel graphics panel, but both gui front-ends appear to work. After all the installation rigamarole everything is stable and the configuration is fine through reboots and hot plugging / unplugging the mini-dp cable to take the SP3 to and from the couch.
The Samsung monitor looks great at 4k. Aside from the troubles getting it installed, I'm very happy with it.
Thanks RIM. Do you think this would be the same trouble with all 4k displays?