Have you heard of the WebOS? http://en.wikipedia.org/wiki/Web_operating_system
Typical drawbacks of such a system is the interoperability with Windows system. Most cannot run anything beyond whatever AJAXified applications that the WebOS author had written. In other words, anything complex beyond Mail, file Management and Photo Management, IM, Word Processor, Excel and PowerPoint is virtually impossible to be run.
Nivio draws a solution taking this into consideration. Nivio runs as a RDC application. What I assume they have written is to use the RDC library available in Windows and wrap it up as a ActiveX application in Windows IE combo. For Firefox and other Browsers + other OS combo, what they have used is to write a (supposedly)thin Applet to run RDC.
(Well, when in this world an applet was called Thin Client, for its bulky memory footprint? :p)
I assume that they have a Load Balancing System that can handle RDC requests from various clients and ensure some QoS on the requests. In my person experience, I have seen that RDC works well when the bandwidth is atleast 256Kbps+ (well it has worked in 64kbps as well, but running something complex that would change the screen often is ruled out).
The biggest question in this whole system is the scalability. How many users can their system scale. It is known fact that a system in RDC can reasonably handle double digit figures to few hundreds of connections. With a server farm of Windows Servers and roaming profile across them, i think they can sustain a decent lot.
There is also another way that they might have implemented. Throw a VMWare server farm, and put a load balancing RDC Connection acceptor that forwards connection to the VMWare Server Pool..
The 2nd one seems much more scalable as VMWare is much more proven than Windows 2003 Windows Terminal Server systems, but in any case, Nivio will have to shell out cash for each client connection (either now or at a later time).
Another question at hand is, when you play , say youtube video, how good will be the change in your screen? Answer currently is pathetic in RDC. It will be tough to see much change. The Nivio guys will ahve to sweat it out in this part, and significant space for innovative solution exists in this area.
There is another known issue with RDC. Sometimes when you see error messages, they are shown in the actual monitor, but donot appear in RDC Client. I have seen this issue when using RDC myself, although I cannot tell with confidence if this bug still persists in RDC, but I hope this issue might have been solved by Microsoft.
Well, thats it for the day. Ciao.