Large scale whole genome sequencing in China and elsewhere

The new issue of Nature has a news story describing the projects that are to be undertaken by a Chinese institute: Beijing Genomics Institute, to sequence the entire genomes of 100 Chinese people, and then other Asians in the future; and a joint initiative by NIH and the Wellcome Trust Sanger Institute to sequence the HapMap folks and others. In addition there is the project "by a team led by George Church at Harvard University in Cambridge, Massachusetts, has begun the 'Personal Genome Project' that will examine portions of DNA from ten individuals who have agreed to share their information with the rest of the world."

I wonder what exactly this guy is referring to in this quote:

...says Rasmus Nielsen of the University of California, Berkeley. “One of the exciting things about having so many sequences from Chinese individuals is that we will be able to say how much genetic exchange there has been between continents since [early humans migrated] out of Africa. That's been very hotly debated.”

Genomics sizes up: China launches large-scale human sequencing initiative.
Jane Qiu & Erika Check Hayden
Nature 451, 234 (2008) Published online 16 January 2008