A rating for Super Mario Galaxy has surfaced on the ESRB website, indicating that the game might be coming to Wii U Virtual Console. Although this is just a rating, these often lead to a game being revealed before its official announcement.
Super Mario Galaxy 2 has been available on the Wii U Virtual Console for quite a while, so it wouldn't be surprising if the prequel would also get released on the system, especially taking in consideration that the game was released earlier this year on the Japanese eShop.
Super Mario Galaxy was released on Nintendo Wii back in 2007. The game was a commercial success, and was highly acclaimed by the press and players in general.