Fans are doing what Nintenwon't by modding Super Mario Galaxy 2 so that it supports split-screen co-op. Bless you, you enterprising coding nerds.
The Wii homebrew community has managed to pull this bit of magic off by using Riivolution, a game patcher that lets users mess with content on retail game discs.
"The mod will not be available for a while yet," says MrBean35000vr, the user that has posted a video of the mod on YouTube. "As may be apparent in the video, some things are clearly out of place; such as the HP meters, which not only aren't on-screen properly, but only show Player 2's HP...
"The camera control is also proving difficult with the two screens, and so Mario and Luigi currently can't stray too far from each other (hence they're together a lot in this preview)."
At E3 Nintendo showed off more of New Super Mario Bros. U.