Google has been using the user's IP address to serve up local results for the Google Local 7-pack for awhile now. Then back in February they added a search "Nearby" feature that would allow you to refine your organic search results as well as the Google Local 7-pack for a city. On top of this Google is now using your IP address to influence search engine rankings for broad terms.
What does this mean?
It means that a user in one location will be served up one set of results while a user in another location will be served up a different set of results for the same search term. It also means so long to keyword ranking reports and hello Google Webmaster Center. I mention Google Webmaster Center because they now have incorporated an "average ranking" for your keywords with the dashboard. There was also some testing done by Google where they were appending a ranking to the destination URL that some say would allow Google Analytics to capture the actual search ranking for the particular keyword that attributed to the site visit. As of today, this has not happened.
So I did a search for "healthcare staffing agency" from my computer. Since we are our own hosting company, our servers are based at our headquarters in Altamonte Springs, Florida. As expected it triggered a Google Local 7-pack that resulted in local businesses near my IP address. Now I used a proxy server that was based out of New York. The Google Local 7-pack resulted in local businesses near the New York server. But the result set for the organic search results in Google were a bit different. I noticed that the New York server had two different listings, one in New York and one in Connecticut.