Reader Andre emailed in this bit of info a long time ago, but I was waiting for more of a confirmation on the news. I greatly appreciate his patience with this topic!

I have seen some of the new screenshots in the most recent Nintendo Power, and they do indeed show a Hammer Bro as one of the playable characters. His icon appears in the player list in more than a couple screenshots. Nice to see some of the lesser baddies from the Mario universe get some MP action. Once again, huge thank you to Andre, as well as The Livingstons for the heads up.