It all comes down to whether it can accept 120hz+ signal. 120hz TVs for the most part cannot. 120hz is a good refresh rate for TVs in Region 1 because it is an even multiple of both 24 and 60, the refresh rates of film and broadcast material respectively. 60hz TVs have to do a 3:2 pulldown on 24fps material which results in judder, offensive to some people but not to others (doesn't bother me at all for example, I can't even notice it
). But a refresh rate of 120hz does not mean that your TV can accept 120hz input, and you'll need that for 3D tech.
120hz "input" not just 120hz "refresh rate"
@phil, remember that not all 3d tech uses active shutter glasses.