Good-looking open-source robot garden here

http://www.adafruit.com/blog/2009/04/27/peter-sands-plant-fasting/

*I don't much believe in urban agriculture, because normal gardening is slow, patient, caring work that quickly bores most people.

*Robot windowbox gardens with net-links, those I almost believe in.
A commercial packaged version of one of these, I might go for that.
A lot of people would pay for automaton gardens. They might even pay for themselves, unlike most hobby gardening.