As much as I grumble about others using their cellphones while driving I use mine too -- kidding myself that it's safe because I have it tucked into the visor on speaker phone.
I read an article in the New York Times this evening that was a bit sobering. The article is called Drivers and Legislators Dismiss Cellphone Risk.
Read it. And better yet turn off your cellphone I guess. I know how easy it is to rationalize it being safe or necessary. A real time saving multitasking life extending invention. I've said those things. I don't believe them anymore. So I'll make a change.