Yes, it's to check for bleeding, clots, etc. It is the worst ever!
I think they just do it right after they take the baby out. I know DD's cord was cut and clamped within seconds of her being out of me. I did ask to see the placenta afterwards...just out of curiosity :)
I have a random question I just thought of...how/when do they take out your placenta? Do they have to wait a certain amount of time while you are cut open to take it out?
One more thing...I had horrible gas pains with c-section #2. Make sure to ask for something if it gets bad. After I took simethicone (sp?) tablets, the difference was night and day.