Samsung EVO 480 *and* stock hard drive not recognised by Snow Leopard installer
The answer in this particular instance was that the SATA cable had come loose. Unscrewing the metal grate housing and re-pressing the connector to the mobo fixed it, and the HFS+ formatted Samsung 840 EVO SSD worked in the macbook pro.

The original hard drive still works, but will now be put in the optical bay instead of the superdrive.