Saw her in a Featured game a while ago. Was a completely retarded setup for a ranked game. 5 'AP' team:
Support Annie, AD Ahri, Fiddlesticks Jungle and forgot mid and top lane. Both were AP though. Prolly Rumble, Vlad or Kennen or some such. Might've been Orianna mid. They were actually beating the other team, though that might just have been the other team being completely gobsmacked.
It just makes sense though, she has good stats for an AD and the skills on her are insane for an AD carry. Hard CC for 2.5 seconds while getting pelted with auto attacks? Repositioning tool that lets you chase and escape? Passive sustain from hits with W that also grants passive harass?
Tried it in a custom game and it's very fluid. Doubt I can convince a team to do it, but can easily see taking her to mid lane as AD carry when you get an AP carry in top lane and maybe an AP jungler.