There's no release date set for Brawl other than Japan (where it's already out) and America (which is March 9th), but if it's anything like Melee then you're going to be waiting a fair while.
There is a Mario Kart Wii in development right now, yes, and it'll apparently come with a steering wheel controller thing that you can use while playing it. Which is pretty neat. Mario Kart Wii is set to be released March 15th in America, April 10th in Japan, and Q1 in Europe and Australia (so October-December 2008 =/).
On the topic of Super Mario Galaxy, I've got 110 or so stars now, and I'm attempting to get my last non-comet star. Details below:
Spoiler: Click here to viewIt's the secret star in the Sea Slide Galaxy, the one where you have to pick up all the musical notes on that prism that's made up of those disappearing green platforms. Does anyone have any strategy suggestions for that? I can never walk on a single path and not have to leap across chasms, and die half the time by falling into the black hole
It's an awesome game though. I love it.