From what I can see--and keep in mind that I haven't used the API yet--there are 3 basic services that the API provides:
- local file resource storage and caching so that you can view files after disconnecting
- a worker pool module for running asynchronous background processes
The obvious use for this is to make stateful applications that continue to operate when you're offline, but maybe there are some privacy opportunities here too. Today, applications come in primarily two varieties: apps with user data and software stored locally, and web-based applications that execute and store data on the server. What I'm curious to see is if developers will begin making a third, hybrid category of application, where software release and maintenance is web-based and global data is available for local consumption, but the storage and processing of user-specific data takes place on the client side, safe from unwanted profiling.
Google Gears API Developer's Guide - Link