I sumbitted applications to UT-Austin, Michigan, and Cornell by LSAC this past Friday. Today, I received e-mails indicating that my application was received by UT-A and Cornell; no such luck from Michigan. Should I be worried at this point?

Nope.

Different schools do it at a different pace. Hell, the same school isn't always consistent.

I forgot if it was Michigan or Northwestern, but it took a few weeks or something like that before they even sent me an email acknowledgment of my existence.

Applied to Michigan same day as you, still no word either. Guess we'll just wait and see.

If you went through Lsac I believe they request a paper report, which takes another week. They probably will not say anything until then.

Michigan takes a little while to send the "application received" email (mine took over a week), so don't worry about it.

Still haven't received mine either. I think they take their time.