Alexis, I just got my first MTB, a Specialized Myka. While I'm not in the market for a FS, I have looked at their geometry just to get a feel for what might fit me. I'm 5'4 with really short legs. I've ruled any number of bikes out because of it. A couple that might fit me are the Specialized
Myka, Pivot Mach 4, 5 and 5.7 and Titus. Unfortunately, these latter two are not cheap.
I'd not that there was someone on TE last week trying to sell her 2011 XS Pivot Mach 5 for quite a bit off retail.

In any event, there's a fairly recent thread in TE's MTB subforum on bikes for short people. I'd link to it, but I'm on my Blackberry and can't do that. Just go to the subforum and scroll down; you should see it. There's also a couple of discussions on MTBR's women's subforum on that topic.

Happy hunting!