There was a discussion on it on these forums somewhere but it seems to have disappeared...
Some people postulated that the release date is hidden inside this post. The post is strange because the contest has no end date, requests that the photo resolution be no larger than 1600x1200 (an outdated and odd resolution), and that the files be no larger than 5mb's.
Put the numbers in order, remove the zero's, and you have 5/16/12 (A Wednesday). A possible release date? I'm surprised this has not been brought up all over these forums... There was one thread about it, but it seems to have been deleted for some unknown reason.
Blizzard has definitely not been known to delete threads that speculate on release dates. They're all over the place. Why would that particular thread get deleted? Is this thread in danger of meeting the same end?
EDIT: There's also this:
Though I don't hold much hope for that one.