On the subject of migrations, although in a very different part of the world, The August National Geographic has an article on some cave paintings of about 10,000 BC in Borneo that tie those people with the early Australians.
I got it yesterday...haven't read it yet.
About the 40k year old footprints, someone's numbers are really off if they are modern. If they are Homo-Erectus then, 'things' (present theories) are really gonna take some revisions. This is a significent find and I can't understand why it's not getting wider coverage.