Also worth noting - when I edit a picture in Picasa and it's in a synced web album, the URL you get from G+ using your method is different before and after the edit. The earlier URL gets you the earlier version of the photo, the later URL gets you the later version of the photo. So changes do not propagate to LJ unless you update the URL in the entry.

Not sure if that is good or bad! But G+ is keeping previous versions of photos, which is interesting...