There had better be at least one new Mario game announced at E3 or a certain mop-obsessed forumer will not be happy.
Mario Party used to be a yearly release, where's Mario Party 9 already? It's bad enough I had to go through 2006 without one, but then 2008 went by, and now we're almost halfway through 2009 and still nothing. Get with the program, Hudson!
What is Camelot working on these days? They should sign on for a new Mario Golf and Tennis game. The Wiilease of Mario Power Tennis on Wii is not good enough because it wasn't designed with Wii in mind. However, it gives a glimpse of how good the game could be on Wii, so a sequel is warranted. Throw in some new courts and characters, add in some minigames designed around the Wiimote, and toss in online play, and that's one heck of a sequel. Ditto for Mario Golf. They'd probably throw in Wii Motion Plus support to try and sell that thing too, but if Tiger Woods '10 is any indication, it should be optional.
How about a Wii sequel to Mario Hoops? They could probably come up with a creative control scheme using the Wiimote's IR pointer, and the multiplayer alone would give it much more value than the DS original. I don't think it sold very well though so this is quite unlikely.
Maybe some other sport which Mario and co. haven't tackled yet could work. I don't know, I'm not a game designer, it isn't my job to think of these things.
There will probably be more details on Mario and Sonic at the Olympic Winter Games, but I hope that isn't all in the way of Mario on Wii.