One of the particuarly dear pet arguments of Christians who think evolution is "just a theory", one no more or less valid than that of, say, creationism*, is that "speciation has never been observed." While demonstrably invalid for quite some time, this BBCnews article provides yet another nail for that coffin:

Scientists at the University of Arizona may have witnessed the birth of a new species.

Fruit flies, this time. Of course, the typical creationist reaction is to drop back 5 and punt with the reply, "well, nobody's seen any big species diverge." We're not here to convince these people, we're here to provide the rest of you ammunition to make them a little less smug in their arguments.

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* Which is, of course, flat wrong. Evolution is a scientific theory because it can be proven wrong. Creationism can't, so it isn't. Period. See, that was easy wasn't it?