The Tecra W50 is a 15 inch device with an Intel Core processor, NVIDA Quadro K2100M graphics and a 4K display running at 3840×2160. It’s aimed at people wanting a mobile workstations for tasks like AutoCAD and SolidWorks, no price yet but you can bet it won’t be cheap.
The other 4K Notebook is the Toshiba Satellite P50t which is a 15 inch notebook that supports multi-touch. It has the same resolution as the W50 running at 3840×2160 and should work very well with Windows 8.1. The P50t will be available mid-2014. I remember when 640×480 was considered good resolution!
Via the Extreme Windows Blog