New finch species seen emerging?

One of the problems in explaining and proving evolution has always been that its timescale is too slow for real-time observations by humans, at least where vertebrates were concerned. However, two researches studying the famous finches of the Galapagos report seeing the creation of an apparent new species in action. On an island with only one finch species, the arrival of an oddball migrant in 1981 set off a chain of events which, seven generations later, has produced a finch with a distinct appearance and song. It's not clear whether this reproductively isolated type can breed with other finches (part of the classic definition of a species), but it seems to be well along the path to complete separation.