Engadget checked out Toshiba's glasses-free 4K 3DTV at CES 2011. The site says the demonstration was pretty impressive, but unfortunately it only works at three viewing positions.
The LCD panel looks about as far away from production as any we've seen with its billet aluminum enclosure and red rope restricting access. The set can only display 4K in 2D mode, which is a-ok with us, and the only demo content was a 3D render of Final Fantasy that was impressive from its three viewing positions. Of course three viewing positions isn't exactly what we'd call practical for our home theater, and the 3D quality wasn't on par with what we've seen from active shutter 3D but it does show solid evidence that Toshiba is making some advancements towards the inevitable.