At this time (October, 2010), there is no requirement to license pet cats in Riverside County or almost anywhere in California.  Long Beach City is the only location this office knows of where cats must be licensed.

There is also no requirement for cats to receive inoculations against Rabies in Riverside County; however, Country Club Animal Clinic recommends that most cats receive at least two such vaccines, with the second being given within a year of the first and after the cat's first annual birthday.  There is a known risk of Rabies from bats in the country, and exposure does not depend on a cat's going outside.  Because the disease is 100% fatal and may be transmitted to humans, the small risk from the vaccine is outweighed by the even smaller risk of human exposure.

Be aware that a recent scam targeting pet owners has surfaced in the Coachella Valley.  Pet owners receive a letter purported to come from an "independent investigative agency" working with the Department of Animal Services, instructing the pet owner to send a "filing fee" or the like to a Post Office Box.  If you receive such a letter, contact your local police department or Riverside County Animal Services.