nvram -p shows "LocationServicesEnabled %01" ... does that mean I have a GPS? What does LocationServicesEnabled mean on a MacBookPro Retina?
Location services do not mean your computer has GPS capabilities but that it is using information that individuals provide, also google or other mapping servicing discover information from wifi broadcasts. Below is Apples take,

Your approximate location is determined using information from local Wi-Fi networks, and is collected by Location Services in a manner that doesn’t personally identify you.

If you allow third-party applications or websites to use your current location, you are subject to their terms and privacy policy and practices. You should review the application’s or website’s terms, privacy policy and practices to understand how they use your location and other information.  Information collected by Apple will be treated in accordance with Apple’s Privacy Policy, which can be found at www.apple.com/privacy.

My take,
This can be fairly accurate as long as no one moves their wifi modem. For an example if an entire neighborhood moved two hundred miles away and did not change any settings (and were not remapped) ones computer would think it was in the original location.