After continued developer requests, Google has added marker clustering to Google Maps SDK for iOS Utility Library. The feature allows users to populate maps with a large number of markers while keeping the map clean and readable. As zoom levels adjust, markers aggregate and slit out accordingly.
Geolocating your users can create a better experience, but it can also be used in devious ways. For example, cathysteeth.com claims to have a cosmetic dentistry solution discovered by a mom. And wouldn't you know it, Cathy lives in your home town. And your home town.