Google (PDF):

This month we kicked off the next big phase of the project: t​esting our prototype vehicles on public streets.​ We’re still all about learning; now we want to know how the community perceives and interacts with these vehicles, and what operational challenges are unique to a fully self-driving vehicle. We’re continuing to test with our Lexus vehicles and we’ll gradually introduce more prototypes to the streets over the coming months.
Activity Summary (​all metrics are as of June 30, 2015)