I was told there were several of these girls dressed like flight attendants in Winter Comiket 2009. According to Mike, the contributor of today's feature, she's "the cutest one in the bunch. Not that all of them weren't cute actually."
Since this is the only photo I have, I can't judge that. Maybe it's because she's wearing her hair in semi-pigtails that it made her stand out?
Anyway, if anyone has any guesses, I'd be glad to hear them! Thanks again to Mike for the contribution!
EDIT: Thanks to anon for letting me know this is a cosplay of one of the many members of Jpop group Passpo!