That was some scary stuff! A lot of time passed between when the controller asked the Cessna to exit, and when he cleared the RJ to takeoff! What the heck was he doing on the runway for that long???!! Something needs to be done about these runway incursions. We've had WAY too many close calls over the past couple of years. Unfortunately, it's just a matter of time.... Everybody stay safe out there! Good job to the Mesa crew, also!