The media often makes out that women are prone to be bi-sexual and tries to encourage women to believe that they could be either that or lesbian. I know that women get confused in their own minds because women react differently than men do. If a man is sexually aroused by a naked man, that would certainly suggest that he is homosexual, but women are in fact entirely normal and heterosexual if they still feel some arousal when viewing sexualised images of women.

This column at Corrupt.org sums up the situation very well and explains how women are turned on by a wide variety of situations and the evolutionary reason for it.

The explanation is that natural selection has favored females who are wet enough not to be as damaged when a male attempts to give them a surprise package. As a woman, I think all this research sums up everything I wanted to know about the female sexual response but never dared to ask! It should revolutionize intercourse on sexual differences.
Why Women Are Hornier Than Men | CORRUPT.org: Remaking Modern Society