The 28" version is single-tile from what I've read. Though it uses TN and is not height adjustable, which is what I need (not going to put stuff under it to prop it up). Next year I suppose.
There are several 4K 28" monitors that are coming about in the summer. However, all are high grade TN panel, and may be single-tile. I am assuming an IPS single-tile will not come out till at least Winter 2014 or after CES 2015.
But if you want a TN-panel, the Asus PB287Q http://www.asus.com/Monitors_Projectors/PB287Q/ is height-adjustable, and swivels, and I am assuming it's a single-tile (won't know for sure until reviews are out). It's release date is June 2014.