goldfish
© Goldfish, by ぱたごん [CC BY-SA 3.0], via Wikimedia Commons.
First, the claim:
Evolution is usually viewed as a slow process, with changes in traits emerging over thousands of generations only. Over the recent years, however, research has indicated that adaptation in specific traits can occur more quickly. However, very few studies outside microorganisms were able to demonstrate empirically how quickly natural selection shapes the whole genome.

A research team led by Dr. Daniel Berner at the University of Basel's Department of Environmental Sciences has now provided evidence for rapid evolution within a single generation, using threespine stickleback fish as model organism. The five-year study combined lab work, field experiments, mathematical modeling and genomic analysis.

University of Basel, "Rapid evolution in fish: Genomic changes within a generation" at ScienceDaily
Paper. (open access)

Zoologist Timothy Standish comments,
This is both fascinating and mundane. The authors seem to have found that if you already have alleles that adapt you to a certain set of conditions, then you will be able to rapidly adapt to those conditions. The speed is impressive, but you could argue that the speed with which natural selection can work is not the real question. The real question is, "How fast can those alleles that make organisms more fit arise de novo in a population that doesn't already have them?"

A secondary question would be, "Could a population survive at all in a changing environment if they were not already preadapted to the changes?" In other words, if organisms didn't already have the basic capacity to survive in a new set of circumstances, they would not make it past the first generation. Where does that resilience come from in a species that is not, like the hybrid fish released in this experiment, already adapted to the new circumstances?

It might have been more interesting to see what happens when you release the lake "species" of stickleback into the stream. How long do they take to adapt to their new environment? Do their acquired genetic adaptations resemble those of already adapted stream species? Were those already present, just in low frequencies, in the lake species? Or do they just die out?
At this point, we can't blame Darwinists for grabbing at low-hanging fruit.