CNN reports:

KENNEDY SPACE CENTER, Florida (CNN) -- The first space shuttle launch since the Columbia disaster could come as early as Sunday but probably will be delayed until later next week, NASA announced Thursday.

Launching Sunday would involve a "really optimistic good luck scenario," said Wayne Hale, deputy shuttle program manager. He said it is more likely that there are several days of troubleshooting ahead.

So it'll be awhile yet before the Shuttle flies again.