But did she perform well? The Disney sweet-tart - who acted as a mentor to the American Idol contestants this week - is taking some hear for her singing last night. Miley performed her latest, "When I Look At You," and admittedly didn't sound her best. I think it's just the type of song? Not a good fit for her voice!

Thoughts???



Real-life gorgeous couple Joe Jonas and Demi Lovato also hit the American Idol stage last night to belt out their duet, Make A Wave. No doubt, the tweens in the audience went nuts!

After the performance, the two young lovebirds gave each other a side hug ... and Ryan Seacrest couldn't resist by saying to the audience, "I'm telling you...good chemistry..."

Way to keep it subtle, Ryan!