I still don't understand the obsession with trying to make consoles into media center computers. I already have a PC hooked up to my TV and, at this point, it is probably fiscally more responsible to be a PC gamer given the direction console and game devs are going with their pricing schemes.
Yeah, my TV handles media better than the PS3 or Xbox 360 hooked up to it, getting media from my DLNA server where I keep movies and TV shows.
I'm not buying a traditional next-gen console. I will probably get a SteamBox and leverage my existing library. None of the new game consoles will play games over 1080p, either.
I suspect Microsoft and Sony have missed the opportunity to launch new consoles with any success. This will be 1984 all over again, perhaps worse when gamers figure out their PCs hook up just fine to their HDTVs now, and they don't have to deal with the relentless DRM the new consoles will enable for publishers (I'm looking at you, EA and Blizzard), or at least have the freedom to make choices. Best of all, PCs will run games from the DOS days, but your consoles won't be backwards compatible.
Outside of using this 4K TV as a computer monitor (it has a VGA hookup, that might handle a faster refresh?), I don't see any use for this. Yes, I know there are "perception charts" that show some theoretical distance/size ratio where you can see the difference in pixels, but that's with highly-aliased/contrasted pixels. You'll never see that in media, and any competent games will anti-alias at 1080p, and you'll never spot the difference, even at a 6" away.
As a computer monitor, I wouldn't care to run games at 3840x2160 - what's the point? I'd need a dual-Titan SLI rig to run that at any decent frame rates.... but my current card will handle 1080p just fine, and look great doing it - so 30hz isn't a killer there - you'd be lucky to get FPS over 30 at that resolution. If the TV's scaling processor is decent, you'll get the benefit of gross anti-aliasing on the scaled-up 1080p output of your computer, anyway.
For a desktop, hell yes, I would love the higher resolution. I run dual monitors already, but the vertical resolution is always an issue for me. I'm a developer, and I always have lots of windows open. 1080p is less than optimal, 2160p would be nice.