Reporting an issue in Social Stream.
I frequently will start an article and set it to publish some days in the future, but only temporarily as I don't want it to post, just save my work as I go. Once I'm done the article, I move it up to publish immediately.
Social Stream seems to grab the original date published in the future and hang onto it, leaving the article at the top of the social stream until that time passes. You can see this below in the two articles that are actually published already, but Social Stream has them on Jan 12th and Jan 17th respectively.