I'm also having the same startup issues as Rikkid6 and tgallien. I'm on an mbp and 10.5.8 - I've seen a few hints here and there, but nothing conclusive/official, that Civ V requires Snow Leopard, which could be why it crashes on startup. Are you (Rikkid6 and tgallien) using 10.5 or 10.6?
And...