I know some of us have been holding out on accepting answers to our questions to allow the site to grow and encourage people to contribute. But, now the site is going into public beta, so should we start accepting answers to questions to show the incoming people what good answers look like?
We should've started long ago. Being in private beta is no reason to hold out on accepting answers. It's fine if you want to keep the question in limbo for a few days to garner more answers (generally, questions with an accepted answer don't get many more answers)--but don't do this for weeks. Remember, the acceptance tickmark can always be undone.
(Not certain this warrants a full answer) but yes, agreed, I think we should. The site is mature and well-defined enough that we should start operating like a normal SO site, ipso facto, accepting answers.