Have BFF's and sex-tape duo of Paris Hilton and Kim Kardashian had a falling out? According to MSNBC, it all boils down to ego because, you know, there can only be room for one celebutante/porn star in this world.

Paris Hilton was a no-show at sometimes best friend Kim Kardashian’s birthday party in Las Vegas on Friday, and the word is that the two are best friends no more because of a clash of egos. Kardashian didn’t want to be clubbing in the partying heiress’s shadow — and Hilton was miffed that her less-famous friend was being called the New Paris, according to various sources — including Kardashian’s former publicist. “Even when I would talk to editors of magazines and other media outlets about featuring Kim, they would comment on how they are moving past Paris in hopes to bring someone fresh to the spotlight, like Kim,” Kardashian’s ex-rep, Jonathan Jaxson noted on his blog.

Wow, earth-shattering news that two chicks famous for nothing more than being from a famous family, shopping and filming their sexual exploits aren't getting along. As one co-worker put it this morning, "Paris goes through friends like she changes her handbags." Anyway, it looks like Kim has found a new friend in Mischa Barton, whose lack of work lately is pushing her out of the actress category and into that same brainless group as Kim and Paris. The two had dinner together at Mr. Chow's (would love to hear what they talked about) and then headed off to The Roxy. More pics after the jump!