Accessing Speed Information with Core Location or MapKit

Implementing GPS and Time-Activated Push Notifications Using Apple's Geofencing Model

Location-Aware Game Development: Rotating Coordinates Relative to a Center Point in 3D Space Using Latitude/Longitude Conversions and Cartesian Transformations

iPhone Web Apps and GPS Positioning for iOS Development: A Comprehensive Guide to Creating iPhone-Friendly Websites That Access GPS Coordinates.