As with the original Super Mario Galaxy, it will be possible for a second person to play cooperatively with an additional remote. The below image, taken from the microsite, seems to show the second player controlling a red Luma to help squash a Goomba. The text describes the two player cooperative mode as even more convenient, with more to do than before.
In addition, Official Nintendo Magazine has revealed artwork of a new power-up, Cloud Mario. This power seems to give him the ability to walk on steps formed from clouds.
I hate it when headlines contain spoilers...
I don't really care, powerups in 3D Mario don't matter nearly as much as they do in 2D Mario, in 3D they're just a cheap way to change the gameplay style of one level.....