Holograms are already here and have been for some time. Ok, they're not the force field-defined sentient beings we know them as in Trek, they're currently just projections of light. But they're coming along. I was actually fooled by a hologram a few years ago; it was a hologram of a small toy. I went to grab it and my hand went straight through. The hologram was soo perfect I still couldn't tell the difference even when I knew it wasn't real, and believe me I tried.
Holographic tv's are in development too. So now all we need is the actual jump to holodecks and Warp drive and we'll be meeting the Vulcans in no time.
