LBS: Good Introduction

If you would like to get acquainted with the idea of location based services and have a quick introduction to the basic ideas and the technologies it is based on I can recommend reading "Foundations of Location Based Services", written by a team of researchers at CartouCHe, a Swiss e-learning initiative on higher learning.

Unfortunately, only this first lecture is freely available, the other documents are only available to project members.

This document answers the basic questions of what LBS are, how they are useful, what is special about them and the technology behind it.

Another good, more technical introduction can be found here. With one simple example (a person looking for a nearby restaurant) it explains the HTTP and XML flows behind the search.

Do you know some other good introductory documents on LBS? Please feel free to post them in a comment!
Cheers!