"Falling Into Grace" by Caintigern O'Niall (Caintigern@deathsdoor). Grace goes to a festival with her boyfriend, who is a bit of a possessive jerk. During a lull in the action, her eye falls upon Phylicia, and the result is mutual love at first sight. Grace lacks experience with same-gender sex, but she learns quickly from the more adept Phylicia.

The story is very well written. The non-sex dialogue and descriptions add to the atmosphere, but they are not overdone. And the sex is just plain hot.