Wow, lots of suggestions. I personally have had success with draper relays. They are ordered as 1 relay per shade/motor, all relays connect to an RS-232 controllable module via 4-wire Rj-11's, and have complete control via the 232, such as single, system or group.

I was very pleased with the success, since this was done by a window treatment company and had left the new homeowners with no way of control, no wall swich or remote.