Wrox’s Beginning Google Maps Mashups is one of the first books available that teaches web developers how to build innovative applications with public APIs.  Mashup master Virender Ajmani skillfully guides readers through mashup fundamentals including REST, XML, and Ajax and then on to creating their own mashups and remixes using the Google Maps   API.  Topics covered include: <ul type="disc">

Using mashup technologies including REST, Ajax,  JSON, SOAP, XML-RPC, CSS and more

Understanding the Google Maps APIs

Obtaining geocoding data

Adding Zoom,Map,Satellite,Hybrid Controls to your mashups

Building mashups from MySQL data

Mashup data from Yahoo! and other services

and more.

Companion website at Wrox.com includes source code.