My due date is a Thursday, and I've committed to work through that Friday if baby hasn't arrived by then. They know that I may come in for an hour or two here and there to give me something to do if I still haven't had the baby, but that Friday is the last day they're COUNTING on my being here if baby hasn't come.
I work in a pretty relaxed environment, and they're happy to be flexible with me. I'm also planning to only take four weeks COMPLETELY off, after which point I'll be coming in the evenings (with the baby) to work a few hours here and there to keep up with some select clients' needs.