P.K.
A bit of background...my SIL is a gay and has had a life partner for as long as I remember, infact, her life partner has been in my life as long as I've known my Inlaw family.
Many conversations surround feeling this way and having desires at young ages. Even my SIL has said that she knew well before she was 10. Perhaps your daughter truely is feeling things, so I wouldn't underestimate her feelings. If she's telling you about it, she's just as confused as you are.
On the other hand, it could be just fantasizing, which is perfectly natural when entering into puberty. She may be experimenting on her own a little and since she hopefully has seen more girls naked than boys (if ever) then the reason for her fantasizing about girls is because that's all she knows, not that you want her to rush out and see naked boys, but the fantasy of naked girls is there in her mind, which is totally natural. She'll figure things out and it's nice that she's being honest and upfront with you about her confusion. Keep supporting her, no matter what her decision, however hard it is. Chances are, it won't come to realization either way until she's well into highschool and with your support, a transition (no matter what it is) will be alot less stressful for her.
BTW: I agree with Tamara's response to Teresa's comments. I think in the larger scope of the G,L,T community can verify that most of them had happy childhoods with supportive parents.