I installed the beta and ran Photo Gallery on a collection of some 1000 photos in order to test the batch detection. It gave me a bunch of options at first, which looked promising, but having gone through the database I discovered LOADS of untagged, unidentified photos.
I tagged a bunch of them manually, hoping that this will cause Photo Gallery to rescan for more matches, but it doesn't seem to be doing that. It is VERY rare that it finds new matches of its own initiative. Is there a way to cause it to rescan for more matches?