I'm working on a fully-automatic farm now that 1.5 is out. The plan is to use redstone to flush fully-grown crops into a channel to be collected by a hopper and then picked up by a cart. The issue I've ran into, however, is that seeds do no seem to be planted by dispensers or droppers. The wiki says bone meal can be used on growing crops from dispensers, but is it possible to plant the crops from either device?
This is my current setup: