Jon, from reading the Google Help files carefully, the search personalization is stored on your computer in a cooky (along with your Google logon if you have an account). Based on results from unscientific observations, once that cooky is set it effects all Google searches, whether from the Google search page or from the Google search field in Safari. One of the ways Google Help suggests to disable the search personalization is to delete that cooky (or all cookies). By the way I just checked and there are 87 Google cookies set in my Safari - I did not attempt to identify which one controls the search personalization.
FWIW I like the search personalization if for no other reason than when I do a search, locations in my physical vicinity will be at or near the top of the hit list. It does me little good to find a plumber or a store in New York when I live in Texas.
