While the Zen Garden Sink is a pretty neat idea, what with the water from your sink running off to feed a plant before going down the drain, and it looks really great, there are a few problems that I can see.
First of all, if you use your sink with any kind of frequency, wouldn't you drown the plant pretty quickly? It's not like a plant needs a neverending supply of water, and I imagine just one face-washing session would waterlog most plants. Second of all, what about all the soap and toothpaste you send down your drain? I can't imagine a plant growing that well when it's clogged with Colgate and Zest. But hey, it looks nice, so that's got to count for something, right?