Thanks for the replies.

Does anyone know when the "computer" decides to release the seats and change my segment from waitlist to confirmed status? Is this something that is done automatically? Or does someone at UA physically have to do it?

What I'm worried about is if my flight date is approaching and I'm still on the waitlist, should I just change to a higher class fare or wait it out? There is inventory in other booking classes but not the cheaper one that I'm in right now.

I'm just wondering what the procedures are for something like this so I can decide what to do. Are the waitlist procedures for other airlines similar?