Just came across this thread.
After Magnus initially wrote the Exif support I rewrote the Exif parsing part of it using php's internal exif libaries, the old code was 1500 lines and we're doing the same thing in ~100 lines now, that rewrite is already live on the testwiki.
It still needs a bit of spit & polish (which I'm working on, see http://bugzilla.wikimedia.org/show_bug.cgi?id=1947)
You might also be interested in the Ogg metadata bug: http://bugzilla.wikimedia.org/show_bug.cgi?id=1948