Nasty, nasty plant! You've gotten a lot of good advice, but I didn't see two of my "tricks" for dealing with the rash. They are "old wives tales" but they've worked for me.
GO SWIMMING! I know it's ugly, and the last thing you want is to go out in public with that red bumpy rash hanging out. But chlorine breaks the bond of the oil to your skin. The concentration in pool water is plenty strong enough. (I've heard of people dousing themselves with bleach and ending up with a worse problem than the poison ivy--I know you would never be so stupid as to do that!)
HOT WATER! Run the affected area under tap water as hot as you can stand it for as long as you can stand it. [of course, being careful not to burn yourself--see above comment ;-)] Hot water triggers a natural numbing response in your body, and you will be itch-free for quite a while.
I saw a segment on This Old House about getting rid of a poison ivy infestment. They put on hooded shirts and long pants, rubber-banded at the ankles and wrists around gloves and old shoes. Goggles and I think they may have also covered their faces. (bandanas?) They pulled it out and threw it away in garbage bags (DO NOT BURN IT! you don't want poison ivy in your eyes or lungs!!), then threw the all the clothes (even the shoes) away, too. Then straight to a hot soapy shower. I'd add ivy block to any skin that could possibly be exposed, too. Any re-growth (and there will be some!) can be hit with roundup or poison ivy killer while it's small. If it's too close to other landscape plants, you can apply it with a paintbrush. The dead plants still have urushiol (the irritant oil) in them, so don't handle them bare-handed either. Just leave them in place for mother nature to take care of.