...needs to start saving MS points NOW.
No solid date has been announced, but reading between the lines, UNLESS A MAJOR BUG POPS UP(wanted to make sure that last point was very clear), then the launch of the store is imminent. (as in the next few weeks)
I know personally I'm going to be picking up a butt load of tracks from the store when it opens, and others here have said pretty much the same.
So just wanted to give everyone fair warning that if you're stocking up for a rainy day...it's gonna be pouring soon