It might just be me, but it seems profoundly silly to implement what basically amounts to a complete operating system in a browser. Why not use something reasonable like the Java or .Net VM to implement your cross platform applications? I think browsers should stay programs to browse webpages and therefore keep their focus on scripting that enables fancier HTML and CSS manipulation. While running Linux in a browser is an impressive feat, to me it is similar in spirit to simulating a Turing machine in the Game of Life.