You need a computer with a network connection and a web browser to communicate with the BCS. Other than that, you will need some temperature sensors and possibly some switches for input as well as some SSR's (solid state relays) for output. The BCS output consists of 5 volt signals at low current, so the SSR's are required to switch higher voltage/power loads.
The BCS runs programs that work in discrete steps, switching between them based upon conditions that you program. For example, you can have a program with a step that monitors a temperature reading and adjusts an output to hold that temperature (e.g. a RIMS tube via a heating element) until a specific condition is met (a time, etc.) Inputs and outputs remain until you switch to a different step. It's a very flexible system that requires some knowledge of computer programming principles, although not as much knowledge as is needed for an Arduino type system.
Check out the wiki and forum at http://www.embeddedcontrolconcepts.com
for a much better explanation.