smart home 24V communication - relays

Does anyone know how could I connect switches that are powered with 24V line to beagleboard by using stuff that clamp on DIN rails. Also I would like to control home lights 220V. What is the cheapest way to do that.

Look at the z-wave.

Easiest way I can think of for either is to use solid state relays. I think crydom makes some suitable units that could be driven directly with a beagle, or worst case beagle to driver chip, to solid state relay. for that matter just use a driver chip to drive a regular relay with appropriate coil voltage, just be sure to put an apropriate diode across the coil.