Mojang AB is currently crunching during the last week before feature freeze. Today on twitter Notch posted these screens of potential moon phases. Issue with the fanbase is that the moon is currently round. So he posted a poll: http://poll.pollcode.com/A0qQ_result
Stupid subject, maybe, but you can't really have phases with a square moon. I'm sort of following it because I'm amused that there are some really heated comments and the poll is currently divided down the middle.
Edit: The poll title implies they will change the sun to match.