What does it mean to be pro-choice or anti-abortion?

Folks incensed at the prospect of a Casey nomination for Senate in 2006 because of his pro-life views could do worse than read this post by Markos, which demonstrates succinctly that it's not always as easy (or productive) to draw lines as one might think. Party lines aren't always so clean either, but his point deserves more consideration. I'm just sayin'...