You're not officially a couple in Hollywood until you've walked down the red carpet together.

So congratulations to Thursday's official red-carpeted couple: Miley Cyrus and Liam Hemsworth, who made their first public appearance together at last night's premiere for 'The Last Song.'

Of course, they are co-stars in the film, so they had every reason to be on the carpet together. But this significant entertainment industry commitment ceremony cements their status as "loved-up."

However, the young duo are still working out the kinks in their united front. When E!online's Marc Malkin spoke to Cyrus on the carpet, she was searching for her momentarily lost boy. "I lost him, so he's not being the best boyfriend right now," she said of Hemsworth. "The whole deal was we were going to be walking together, but then I lost him first thing because he started saying hello to everyone."