@Paul Orwig: The Gears API is a pretty good starting point for your client needs. Right now I developing location based services for the architecture platform www.archinform.net with similar needs. For evaluating the position of the user by Javascript, there are three usable ways right now available:
1.) Google.ClientLocation: (Part of the Google AJAX API): http://code.google.com/intl/de-DE/apis/ajax/documentation/#ClientLocation Location precision: city level or less, available not for the whole world right now. The users IP is the base for the location. This information is available without asking for user's permission (and without any necessary browser extension) 2.) Google.Gears: Browser extension for several (but not all) platforms+browsers. Preinstalled in the android browser, on all other browsers users have to install the Gears extension first. Gears can calculate location based on WLAN/Wifi, cell towers and GPS. WLAN/Wifi works pretty well and allows to find position for desktop and laptop computers (if they use WLAN), in Berlin for example this works perfectly for me. As far as I know GPS support for Gears is in the beginnings, but hopefully more and more devices will be supported. 3.) the new Javascript navigator object: This is a W3C draft (supported by Google) for a new standardized way to get access to a users loc by Javascript. The next version of Firefox 3.1/3.5 (beta) already supports this object. I believe, that this will be the future standard. There is an interesting approach (see: http://ajaxian.com/archives/navigatorgeolocation-using-the-w3c-geolocation-api-today) to combine these three ways. I implemented this code on http://www.archinform.net/index.htm (if location detection is possible, You will see a list of the next ten notable buildings around You, otherwise a message to install Gears (on supported platforms)). @Robert: Thanks for the blackberry link, I will try to include this into the ajaxian code. About precision: WLAN/Wifi and celltriangulation's precision is not too bad and You have to keep in mind, that a big portion of GPS enabled smartphone users disable this function most of the time, because the GPS chipset needs a lot of power (btw, as far as I know the Gears on the G1 phone can use the GPS chipset) Sascha
