There are a number of products out there, and the details differ. I'd check local commercial / government jobs, and see what they're using. See who the architect they use, and ask the architect for his preferences. Also, Wal-Mart has been using remotely controlled Square D QO circuit breakers for at least a decade.
The newer systems differ in detail, but the installation is similar. They involve mounting a lighting control panel near the breaker panels, and taking power from existing circuits.
From these lighting panels are run low voltage cables to brand specific light switches. Other components in the panel allow for automatic and remote control.