VIDEO: Demi Lovato celebrates release of Princess Protection Program in Boston

The king of pop is dead. Meet the Princess. 

DEMI LOVATO is 

When DEMI LOVATO took the stage at Agganis Arena earlier this evening, the only top trending topic on Twitter that was not related to Michael Jackson's death was PRINCESS PROTECTION -- a measure of how many girls were, at that very moment (and still as of this writing), tweeting their faces off while watching the Disney Channel debut of Princess Protection Program, Lovato's first big feature production. Disney expects that PPP will launch Miley Cyrus-like careers for Lovato and her co-star Selena Gomez, a childhood friend whom she met when they were both cast members on Barney and Friends. You can think of Disney's tween-pop factory as the last vestige -- or an unlikely re-emergence -- of the old Hollywood studio system. Its child stars are well-groomed, infallibly humble, hard-working, pragmatic entertainers. Bit players learn their craft as apprentices to Disney's stars and bide their time. Not all of them ever make it to A-list status: Mitchell Musso, the actor who plays Miley Cyrus's brother on Hannah Montana, is a big Radio Disney star right now, but he seems on a path to follow High School Musical also-ran Ashlee Tisdale down the road musical character actors.

Lovato, however, has already begun laying the long-advance groundwork for the delicate process of crossing over from Radio Disney to Top 40. After starring alongside the Jonas Brothers in the Disney telemovie Camp Rock, she hit the road as their opening act; they also co-wrote several songs on her debut album, which shot to Number 2 on the Billboard charts in September. While on tour with the JoBros, Lovato let slip to Rolling Stone writer (and former Phoenix staffer) Jason Gay that she'd grown up listening to metal. Later, she impressed MTV's resident metalhead by name-checking Dimmu Borgir and Lamb of God. (It had been rumored that Disney rejected an early verison of Lovato's debut for being "too dark.") And earlier this year, Lovato appeared on an afternoon slot at New Jersey's Bamboozle fest, braving what could have been a hostile audience of dyed-in-the-wool punk fans. But at Agganis she was pure Disney: "Tonight is a very special night for me, because tonight I'm a princess," she smiled from the stage. "Who's TIVO-ing it right now?"

Lovato had a difficult night. About four songs into her set she went suddenly hoarse and reedy, and she struggled to smile through what she clearly realized was a shaky performance. At 16, she's already a showbiz pro -- during one song she came across a note she couldn't hit, and rather than miss it, she pretended she'd forgotten the lyric. There is something heartbreaking about