I'm a newly out lesbian, and I've recently realized I'm attracted to my best friend. We've been hanging out a lot more lately because we work together. But, I've been staying over at her house more lately because it's easier and saves on gas. During the past month, I've become more and more attracted to her. I don't know if she feels the same way about me though (although I think she might). Lately when I stay at her house (she has two twin beds in her room) she switches her bed around so that her head is near my bed. She also pokes me playfully (something she never used to do) and calls be daily, even if we have seen each other all day (and we talk for hours which we never did). The latest development is that I am going to be house sitting for my brother and she wants to take the time off work to come stay with me.

We've been friends for many years and I don't want to do or say anything that will ruin our friendship. Is she attracted to me or is it my own lust for her? What do I do to not ruin the friendship, but let her know I am interested?

Your situation is one that many newly out lesbians have lived through. I always suggest a discussion between the two. I have known some who have lived as partners for decades and wished they had told each other of their feelings earlier. Others have indeed lost a friendship. I think much of the outcome depends upon your ages and life experiences.
If you lose her friendship by opening up to her, she was not your friend to begin with.