RJ was right- in fact, you don't even need to remove the plastic column covers! Stick a piece of coathanger in the hole, and with the key in the "on" position, pull the cylinder straight out.
Ford stocks the new ones, either by itself, or with matching door cylinders for under $100. When I bought my truck, mine was so worn out, I couldn't ever get it to the "off" position properly. I replaced both door cylinders and the ignition cylinder. (IIRC, the door panels don't have to be removed for the door cylinders, either...)
Ryan