Like many other NAS vendors, Thecus implements the same feature set across its NAS lines. Nothing has really changed since I summarized the current feature set in the recent N4800 review.
Actually, when I checked the list of installable modules posted online vs. the one shown by the built-in Auto Module Installation page (below), I found a new one: the Local Display Module.
Installable module list
Local Display appears to be a work in progress. There is no documentation yet for the module, but it appears to offer two options. You can launch a built-in copy of FireFox for Linux, or you can launch an x terminal to access the system console.
I was able to browse to the NY Times website and watch some of the videos there (including sound via HDMI) using Firefox and a USB keyboard and mouse I plugged in for navigation. I wasn't, however, able to view any videos stored on my network. I also tried installing the Twonkymedia server, uploading an H.264 encoded movie trailer to its video folder, browsing to it and trying to play it. But the browser didn't know how to deal with it. So it will be awhile before you can use the N6850 (or more likely, the N4800) as a media center.
For more feature details, you can use the online emulator.