No announcements yet, but a quote from Mr. Jobs in Time from an interview with Apple's CEO has the following exchange:

TIME: What about independent labels? Will they follow suit?

Jobs: Yes. They've already been calling us like crazy. We've had to put most of them off until after launch just because the big five have most of the music, and we only had so many hours in the day. But now we're really going to have time to focus on a lot of the independents and that will be really great.

From this, I'm going to take away that there is hope of getting some of those catalogs online.

To vote with your mouse, make sure you go in to iTunes and tell Apple you want to hear from your favorite artists and labels.