When user's click on My Profile, the details entered are displayed with a link to a Search Center whic refines that link.
E.g. if your country is France, you get a link to a People Search which searches for other People whose country is France
[http://site]/SearchCenter/Pages/PeopleResults.aspx?k=Country:"France"
In case you wanted to change the Search Center to direct the search to (Preferred Search Center), you'll find this setting in the My Site settings in the Shared Services Provider.
