“At the heart of every location-based application is positioning and geolocation. In this tutorial you will learn the geolocation capabilities of HTML5 and the basic principles needed to take advantage of them in your next HTML5 app!”
Nettuts+ sister site Mobiletuts+ has just posted a fantastic entry-level tutorial on using HTML5 for Geolocation with your mobile web app. If you’re interested in HTML5 and mobile development for mobile devices, make sure to check out the tutorial!