California SB 1298 would expressly establish that California "presently does not prohibit or specifically regulate the operation of autonomous vehicles," direct the Department of the California Highway Patrol to "adopt regulations" regarding "specific safety requirements for the testing and operation of autonomous vehicles," and "not prohibit" such operation and testing prior to those regulations. The bill does not say who (if anyone) drives an autonomous vehicle in the legal sense, a question I asked about California's motor vehicle code in a post last month.
The bill's autonomous-driving-is-already-legal approach is similar to a proposed amendment to Florida HB 1207. Unlike California SB 1298, that amendment expressly states that "a person shall be deemed to be the operator of an autonomous vehicle operating in autonomous mode when the person causes the vehicle's autonomous technology to engage, regardless of whether the person is physically present in the vehicle while the vehicle is operating in autonomous mode." (But what if an automated system engages the autonomous technology?) Another amendment would address liability following conversion of a vehicle to an autonomous vehicle.
Meanwhile, Arizona's bill failed in the House Transportation Committee after members expressed concern that it was too much too soon - that is, the technology was not ready and the rulemaking burden on the state's Department of Transportation would be too great.
For a summary of all legislative and regulatory developments, see my wiki.