I don't think we ever found out what RISC stands for, but it's connected to the Rhodes Foundry on Devil's Rock. The Tripods and the Centaur/Simian battle armor are labeled as RISC projects.
The RISC tech discussed here was a wide variety of items that showed up after the Republic walls went up. They were all of the 'high risk, high reward' variety (Hence the name) and tended to show up all over the place.