One of my colleagues has made this work (in 2.5), but it wasn't ported over to our latest major upgrade and he's not had a chance to try since.
We only used it on the 'enrol users' popup, as some of our staff here have student logins as well for courses they're studying, but I remember it taking a while to find the right place in the code for it to go.
This gist of it was, in the right place - get the picture attribute in AD, render out the image as a binary data img tag.
I'll see if I can dig out the code from the previous instance, assuming it's still on the server.