Wow, do I disagree with the idea of a bridge camera.

If your budget is $500, seriously consider an older model dslr with a 50mm f/1.8 lens.

Why?

1. Prime lenses force composition. There's no other way around it-- in order to get the shots you want with a prime, you have to think about what you're doing. Zooms offer a shortcut in this regard that is great if you know what you're doing or don't care, but if you're learning, a prime is essential. With few exceptions, pocket cameras and non-dslrs do not have primes.
2. Speed. A DSLR is simply a faster, more responsive camera. If your daughter is serious about this, serious enough to have you consider buying this much kit, then the shutter lag in a point and shoot (even a g12) that will happen in anything that's not broad daylight will be very frustrating. DSLRs are simply more responsive, because of the way the focusing mechanism works.
3. Serious depth of field capabilities. Apertures of 1.8 on a larger chip make for more background blurring and focal isolation. It is possible to experiment with this kind of thing with a non-slr (for instance, with a canon s95), but having the entire range is extremely useful, especially for experimentation.
4. Image quality. A $400 slr, with its larger chip, should easily best a bridge camera or a point and shoot for image quality. Cameras in this range should definitely offer RAW processing (which she'll want if she wants to experiment with the full range of image processing), but even so, the larger chip and pixel size in a dslr make it hands-down better than a same-generation point and shoot or bridge camera. The exception to this would be something like the olympus ep-1, which has an slr chip in it and should give comparable quality (but is, I think, outside of the price range you want).

I taught a class recently filled with high school students who wanted to get into photography. Those with SLRs could easily grasp the concepts of the lessons because these cameras, by and large, have the controls to manipulate image quality, and these controls tend to be very intuitively available, once the user knows what to look for. Students with a point and shoot or a bridge would struggle to be able to set aperture, shutter, ISO, etc, because each camera manufacturer is different not all of them offer all the requisite functionality to really learn image capture.

So, go for the DSLR, 50mm kit. Then she can save her pennies for other lenses or gear as she needs them.

EDIT: As for particular brand, it depends on whether or not this is a surprise. If it's a surprise, any of those you've listed will work, though, as I pointed out, bypass the kit lens for the 50mm f/1.8. If it's not a surprise, then have her try the bodies out in the store to see which ones fit her hands the best. I personally dislike the entry-level Canon bodies because of my enormous hands, but she may like them for exactly the same reason.