Count me among those who find girl-on-girl sexual activity very exciting. I use the phrase "girl on girl" here instead of "lesbian" because so many of these young women do not identify themselves as lesbian, although of course some do.
I just finished reading Middlesex, by Jeffrey Eugenides, a fabulous novel narrated by a man named Cal who used to be a girl named Calliope. It includes a vivid description of a girl-on-girl love affair that describes the most intimate details with amazing clarity but without a coarse thought or word. Eugenides reminds us how sexual exploration in adolescence takes place under the cover of alcohol, or drugs, or simply keeping your eyes closed and pretending it isn't happening at all. Don't misunderstand me--the book is not a sexual frolic, but an amazing journey through Detroit, and America at large, for a child born with ambiguous genitalia into a memorable Greek immigrant family. I can't do it justice in a sentence and won't try; let's just say it's a good read.
Back to girl on girl activity -- in the case of the photo on this page, I don't know if these women self-identify as lesbian or not, there was no caption posted with the photo:
There is so much to love about this kiss. That the girls were hot enough for each other to kiss on the stairs. Their breasts touching. The hint of ass crack for us to admire. And the way the girl on the bottom holds her friend's head with one hand while pulling her thigh closer with the other.