Update: New Panels Planned from LG.Display and Samsung
http://www.tftcentral.co.uk/news_archive/35.htm#panels_update
A new 31.5" IPS panel (part number tbc) with "8K4K" resolution of 7680 x 4320.
This has a 280 ppi and spec wise it offers a 14ms G2G response time, 1300:1 contrast ratio, 178/178 viewing angles and 400 cd/m2 brightness.
It is not expected to go in to production until Q1 2017.

27" LM270WR5 IPS panel with 3840 x 2160 Ultra HD resolution.
This panel is expected to go in to production around October time and will offer a borderless design (Neoblade III).
It will offer a 14ms G2G response time, 1000:1 contrast ratio, 350 cd/m2 brightness, 178/178 viewing angles and Adobe RGB colour gamut.

The 31.5" LM315WR1 IPS panel we saw mention of before, but now we have some further specs for this panel which is expected to go in to production around Q4 2016.
We now know it will offer a 3840 x 2160 Ultra HD resolution, 14ms G2G response time, 1000:1 contrast ratio, 350 cd/m2 brightness, 178/178 viewing angles and sRGB colour gamut.
This panel is a borderless design (Neoblade III) as well.