The Hologram, "...invented in 1947 by Hungarian physicist Dennis Gabor (Hungarian name: Gábor Dénes) (1900–1979), work for which he received the Nobel Prize in Physics in 1971" - as the wiki says, has come a long way and in many incarnations.
Here's another link which gives an excellent idea on how a hologram works.
Having two eyes (and two ears) separated by a distance between them gives us humans what we call the 'stereo' capability; which when roughly explained means the ability to estimate the location of the 'subject' object / sound in a three dimensional space. However, we've been generally quite satisfied by two dimensional capture and reproduction of photographs (I keep a collection at picasaweb :) ). Thanks to broadband internet, good web-cameras, processors and displays, web-conferencing has become a reality. Add to this the growing cost of travel, fuel, time and our new-found concerns for our fragile ecosystem- now we have a good business case for people to arrange 'meetings' over the web.
Still, even an HDTVish quality web-conference for most business is not as 'good enough' as a face-to-face. I don't know how exactly, but I'd trust my sales friends when they say that it just doesn't cut it!
Anyways, despair not! If the folks at Cisco and a UK based company Musion have their way, you'll soon be able to literally transmit the whole of yourself in all its three dimensional glory to anywhere you'd want to be present - over the net, of course.
Check this demo video out that my colleague Abhinav at Eko shared with me a few days back:
This is an actual demonstration by Cisco at Bangalore!
Going through the Musion site, I was surprised to find this video where they say the Tatas used this at the Nano unveiling at a car-expo at Delhi!
I'd still believe that this will be history soon and B2BC (Brain to Brain Communication) as I had mentioned in a previous post will prevail. Ah, flights of fantasy!