While the basis for this announcement was offline Gmail, the Google Gears tool upon which it relies can enable offline functionality for virtually any site. There is even a Geolocation API which uses WiFi antenna data, which sounds good from a development point of view.
From Google Gears:
Gears is an open source project that enables more powerful web applications, by adding new features to your web browser:
Let web applications interact naturally with your desktop
Store data locally in a fully-searchable database
Gears is a plug-in that extends your browser to create a richer platform for web applications. For example, webmasters can use Gears on their websites to let users access information offline or provide you with content based on your geographical location.
So what applications will it have? Can field researchers such as anthropologists, who may rarely have access to a reliable Internet connection, make use of the service, not only for emails, but for data storage? The idea to allow virtually any website to synchronize data when a connection becomes available might be particulary suited to field research in remote areas.
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