Junk DNA is the term given to long segments of DNA that scientists had assumed for many years simply had no function. It was believed to be vestigial, like an appendix, or the result of duplication of genetic material that subsequent mutations rendered inoperative.
At the same time intelligent design theorists predicted that it would one day be shown that junk DNA wasn't junk at all but rather had some function in the organism. This was a clear case of a prediction that could be verified and would lay to rest the claims of critics that ID can't be empirically tested.
Now it turns out that the predictions have indeed been verified. Junk DNA does appear to be operative during early development.
Darwinians are now retroactively asserting that this is to be expected as a result of natural selection, but the point is that ID theorists had been predicting this all along, whereas the Darwinians, including Ken Miller and Richard Dawkins, were saying the opposite.
There's a story on this at Wired which, despite its annoying tics (the author insists on calling Michael Behe a creationist), gives a good overview of recent developments in this matter.
The folks at Uncommon Descent are indulging themselves in a little understandable gloating.
RLC