One problem that frequently crops up in betas is when you have several different branches of your development repository bugr get fixed on one branch and never make it to other branches, thus never make it into the final releases.
You have programmers and designers standing around thinking they've already fixed problems, and they, or other people, have to go in and fix them a second or third time, or not at all. And beta testers are thinking "we reported that and they fixed it, why is it broken in final?" or "they fixed this in such and such a way why did they go back to the old way?" types of things. The support people get all the calls but the devs don't always hear the issues, and realize what's happened.
