Can Unity do Light Trails?

See this video for an example: http://www.youtube.com/watch?v=qTnFL0db2h8

Seems to be done with the KY Trail plugin for 3D Max, is there any way to accomplish this within Unity?

Yes, see the Unity procedural examples @ http://unity3d.com/support/resources/example-projects/procedural-examples.html - that's similar to a Tron trial, and you can just add a bit of glow and particles to tweak it to suit