Google recently put out a new webmaster help video with Matt Cutts discussing how to target parts of a site to different locations.
The exact question Matt addresses in the video is: “Webmaster tools allows site owners to specify a geo location for targeting. How can this be done for multiple locations?”
“It turns out there’s a very easy way to do it,” says Cutts. “If you have a domain, you can add, for example, sub-domains or sub-directories as separate sites in Webmaster Tools.”
“And then once you have those added as separate sites, you can geo-locate or geo-target those individually,” he adds.
Watch the video for the rest of his explanation.