Tabata refers to the structure of the exercise, not the exercise itself. So you can do a lot of exercises tabata-style by doing as many reps as possible for 20 seconds high intensity, then resting for 10 seconds for 4 minutes total. There are lots of different ways to do it, although it's usually done with a strength exercise (for cardio it's called high intensity interval training or guerilla workouts or intervals, or a million other things
). Some people prefer 10-15 seconds on and 10-15 seconds off for 5 minutes, etc. The key is to maintain high intensity so that you never fully recover before you have to go again.
Some people prefer Air Squats (squats without weight) for Tabatas, and some people like different exercises (Thrusters, Burpees, etc.)
I think the thread you're talking about is this one -
http://www.3fatchicks.com/forum/showthread.php?t=164194
It links to this youtube video showing tabata squats -
http://www.youtube.com/watch?v=aBEeH...eature=related
They are hard but very effective! I prefer Dumbbell Thrusters because they get your entire body, including your arms -
http://www.youtube.com/watch?v=peLFTePbfDQ