Can I just add that its possible to do this effect in Premier (or at least you can in Premiere 6) using the colour pass from the video effects. Its done in pretty much the same way as is explained above by bgarthp.
Its a bit simpler so if anyone just wants to try out the effect quickly its a good way to experiment with the effect, without the hassle of getting to grips with after effects (which i am still doing and it still seems exceedingly complex, but thats good, I get the impression you can do anything with it!)
Great effect by the way. I tried it with road signs on a car journey.
AMD XP 2000+
NVidia GeForce 4 Ti 4600
120 GB Hard Drive (Pretty much full due to video editing, ahhh)
DVD Writer 4x
Win XP, Premiere 6.0, After Effects 6.0, Encore DVD 1.0