WSDOT has been encouraging them for a few years now, and my town has several new roundabouts as a result -- and lots of other cities across the state are using them. They've made navigating those intersections way easier, reduced traffic "waiting times", and generally improved safety versus a lighted intersection. I'm glad they're continuing to find ways to make them work.
It seemed when I was growing up in NJ, the state DOT was taking out the giant roundabouts that they were famous for, and now in Washington, they're having a huge resurgence.