Some TVs work with a fairly locked down version of linux, some people sought to gain root access and have done some interesting things though homebrew for them of the high end emulator persuasion is a different matter. If the browser is up to a bit you might get away with some of the javascript/html5/webgl stuff though most browsers I have seen on such TVs is barely enough to load static HTML (probably still better than Wii or PS3 mind you).
This. My kids have a high end Samsung Smart TV from early 2012, JavaScript animations seriously suck. I also thought for a while that it didn't support CSS transitions or animations, but it turned out that it did support them but maxed out at around 1fps for a simple fade-in. It does support HTML5/canvas (not webgl), and also Flash. The newer, dual core Smart TVs might fare better, but probably not enough to run anything more than a NES emulator, if even that.









