Here is a ScienceDaily article about a recent study that features a species of fruit fly in the process of speciation.
Basically, some scientists studied the genetics of various populations of this fly (and a parasitoid* wasp that uses the fly as a host), and determined that the population that lays its eggs in apples is distinct (and essentially isolated) from populations in other fruits. The parasitoid wasp populations that parasitize the apple population of flies are also distinct from populations the parasitize flies on hawthorns and other plants.
Apples have been in North America for under 200 years. Thus, the apple-dwelling population of this fly is also less than 200 years old, yet it has diverged genetically in that fairly short time. This is exactly the process that the Theory of Evolution predicts will lead to speciation, and this species seems well on its way.
Here is a link to the abstract of the original article (I think you'll need a subscription to
Science magazine to view the full text, but maybe not). I think I actually saw these people give an oral presentation on this at a conference last December.
*For those of you who are interested, a "parasitoid" is an insect (usually a wasp or fly) that lays its eggs inside a host animal (usually an insect, worm or slug), and the larvae consume the host. This differs from a parasite in that the host is completely consumed, so the impact of a parasitoid on the host is more akin to the impact of a predator than a parasite.
-Bluejay/Mantis/Thylacosmilus
Darwin loves you.