Was looking around on PopDirt.com and they had this piece:
The Guardian reports that after being emboldened by such images as Madonna kissing Britney Spears and Christina Aguilera on the MTV Video Music Awards, girls are proudly declaring their alternative sexualities at a younger age than ever before as a wave of "bisexual chic" is sweeping America. "I don't think it's possible statistically to say it's increasing, but it seems more girls are comfortable to identify themselves as bisexual," said Denise Pell, president of BiNet USA, a network for bisexuals. "For some, it may be what they really feel; others may be questioning themselves and their sexualities; and it's possible that some are doing it because they think it's chic. It doesn't necessarily mean these kids are sexually active, but they are learning about themselves, not just in their sexualities but in their lives in general. And that should only be encouraged."
there's a link to the full story here: http://www.taipeitimes.com/News/world/archives/2004/01/05/2003086463
personally I don't think the MTV Kiss or Tatu inspired it I think it reflected what was already there, and it's not really a growing acceptance of homosexuality more a growing acceptance of using gayness to titilate straight men. I mean do you see Justin Timberlake and Pharell Williams tonguing at the VMA'S? no. (although that would be very hot :>))