Popular Science has a short article covering recent research into European population structure:
To the delight of genealogy buffs like me, scientists recently announced in the journal Nature that they can trace European ancestry to within 192 miles by analyzing tiny inherited markers in DNA. That means someday we'll need look no further than our own genes to locate our motherlands.
The study, and another much like it in a recent issue of Current Biology, harnessed the stream of human genetic data now being gathered by pharmaceutical companies. Using modern “gene chip” technology, researchers can screen 500,000 units of DNA at once. The companies use the data to investigate the genetic basis for adverse drug responses. But population geneticists are taking advantage of the high-resolution databases too, scouring them for trends in human evolution that are otherwise hard to find.
That's me, I guess. They're calling it a "DNA GPS", which is pretty clever.