I'm shopping dirt/trail bikes now. I've been reading a thread on ADV Rider about short women and their bikes, and I've put together a short list of bikes to look at. This summer I sat on a woman's Honda CRF230 and really liked it. (she sat on my GS and loved it too. I don't think her husband was too happy about that...) The CRF and a couple others are at the top of my list. When I get around to narrowing it down and buying a new bike, I'll let you know what I chose.
If you're a short girl looking for a bike, or a guy looking for a bike for your short girl, check out the ADV Rider thread. It's called "The Shortypants Thread: We are short women and this is what we ride." It has great bike info for shorty girls, and inspiring pictures of woman riders of all ages.