4K TVs: What They Are and Why You Want One

Right now, a full HD TV has 1080 pixels from top to bottom. The upcoming wave of TVs, called 4K TVs, has just under 4000 pixels from top to bottom.

Update: LG has announced a 84-inch 4K TV that will ship next week fro the great price of $19,999.99.
Sony has one, beautifully named the XBR-84X900 coming in November (also 84 inches) which will be $24,999.99
Both of these TVs will also be 3D, for those of you who care.