People that talk on cell phones while driving have important business to take care of. You should move out of the way, or give them extra consideration. Just because they are more important than you, does not mean you have to get upset. If they don't pull out right away, when a light changes, it's just because they are involved in a conversation. Just back off a bit and give them some room. And if they can't stay in their lane, because they are dialing a new number, just be patient. After all, you're in their way. You could pull over and let them pass. It would only take you a couple of minutes to pull over, stop and then continue. If they run a red light or stop sign and you get hit by a driver trying to get out of their way, well, it would be your fault. Look at all the trouble that would cause you, getting your car banged up, a traffic ticket, and spending a lot more time being late, yourself, than if you had just pulled over, before all this.
Lets face it, if you're upset about people on their cell phones while driving, just understand, they have more important things to do than listen to you. Learn to live with it. You're not the most important person on the road, and don't you forget it.