I have long been excited about HTML5 having access to a geolocation data. It should make it possible to build a whole range of applications for phones and other devices that are cross platform but make use of the users location. Unfortunately reality bites when you try and actually build an application based on the technology.
I have been working with Sencha Touch and the Ext.util.Geolocation object but am having problems with accuracy. I have noted the following behaviour.
When I call for a location on iPhone (3G) and iPad (v1) I get a one with around 1.3km accuracy. Basically it places me at one of two spots about 1km apart. If I switch to the native maps app then it places my position within 10m of where I am standing – that “wow it knows where I am” accuracy . Switch back to my web app and the first call to the GeoLocation returns similar accuracy. Any subsequent calls return the old inaccurate positions.