I don't know where you are located. But in the Hampton Roads, Virginia area, there are a lot of church affiliated pre-school programs that take two year olds who aren't potty trained. If they don't take two year olds, they usually take them at 2 1/2 and expect them to be potty trained. In Northern Virginia and Maryland the starting age seems to be fixed at 3 for a two-morning per week program.
My daughter went to pre-school because she is an only child and she needed the socialization (I'm an SAHM who doesn't stay home)and she started at two. The first two years were great; her four year-old-teacher was horrible and we really had a rough year. I should have taken her out of that class when my insticts were telling me to (mostly because I was getting yelled at by the teacher for being a bad mother). After another horrible year in Kindergarten, I finally figured out the teachers that she has had for the past two years are verbally abusive. So, be aware that not all of the teachers in preschools are of the loving, nurturing type. I can understand not putting up with kid BS because I don't either, but you don't have to be nasty about it. Not every teacher, no matter the program, is going to love your daughter the way you do.
A friend of mine put her two boys into Montessori because her sister is a Kindergarten teacher and she highly reccommends the program.
Virginia has the Smart Beginnings program, though it seems to be more of a private business trying to make money than a state program. I looked at their website once and found it unhelpful. Supposedly it is accrediting daycares and pre-schools, so if you live in Virginia it might be worth looking into.
Best wishes to you and your girl. May you find the perfect school.