I haven't seen a discussion of the details in a while but at one point, if you were on the show at all (even if they showed your audition on TV as one of the "bad" ones), you were bound to E19 for a time period. If you're in the top 10 (top 11 this time), you are definitely bound to them for at least a year while you're on tour and possibly a little bit longer. I believe the winner is under contract for 3 or 4 years? I don't remember exactly, but it's definitely a long period of time.
Found a couple links with some info. Looks like it is now based on number of albums produced:
http://www.popeater.com/2010/05/13/a...acts-revealed/
http://dir.salon.com/ent/feature/200...act/index.html