It has been about 8 years since I have done any water sports.  I used to kneeboard and wakeboard.  Are they still popular these days?  I don't typically see anyone doing anything.  Is the black magic kneeboard still a good one?

People still wake board but the new thing is "teak surfing". The ski boats make such a huge wake now (design feature) that you can actually surf behind them close to the swim platform. Swim platforms used to be made primarily of Teak wood hence the name.
In fact, there were people teak surfing out at the lake I work at today.

Sorry but that is not correct.  Teak surfing actually refers to a practice of people laying in the water and holding onto the swim platform (lots of times made from teak), while the boat it underway.  What you are referring to is called "Wake Surfing".  It, unlike teak surfing, is very safe and fun as hell.  It is not as brutal on the body as wake boarding and is pretty easy to learn for beginners.

This is the way I understood it as well
I have done neither though