Gears contains three components:
Store data locally in a fully-searchable relational database
Make your web applications more responsive by performing resource-intensive operations asynchronously
The offline version is updated automatically everytime a user reconnects so long as the online versions “manifest.json” file has it’s version number properly incremented.
Overall it looks really slick and I can’t wait to dig into it a bit. You can check it out at http://gears.google.com