Sorry, my magic 8-ball is not working today...
I have heard they are working on 2160P. Technically there are 2160P's available now in the 52" size that would set you back $40,000. That is 40K and not 4K.
An 82" Samsung model is described as follows: The prototype display has a massive 82 size and features a resolution of 3820x2160 pixels, which results in a total screen resolution of 8.3 megapixels. Current 1080p TVs run at 1920x1080 pixels or 2.1 megapixels. According to the manufacturer, the TV integrates a red/green/blue LED backlight, which raises the color saturation to 150%. The image refresh rate is 120 Hz.
If you want to read about it go here. If you want to buy it you better win the lottery.
http://www.tgdaily.com/html_tmp/content-view-37511-97.html
Now if you really want to go bannanas then there is http://www.engadget.com/2005/11/05/nhk-shows-off-some-live-7680-x-4320-super-hi-vision-tv-in/
NHK shows off some live 7680 x 4320 "Super Hi-Vision" TV in Japan running at 7680 x 4320 16 times the resolution of that lame old 1080i your grandparents are talking about.