Here are a couple of videos that show in detail how the Garden Tower works. I wrote about it back in April. Although I have no hands-on experience, it looks to me to be a productive new way to grow some fresh vegetables in confined urban spaces. Go to Kickstarter if you are interested in supporting this new system.
The vertical "African sack garden" form and Larry Hall's rain gutter sub-irrigation system are two of my favorite urban food production concepts. I believe we will see a variety of these systems in widespread use in the future.
I'm looking forward to gaining some first hand experience in the current growing season as my new knee heals. I have several ideas to test.