Lots of folks are talking about Google Gears, an open source browser extension that enables web applications to provide offline functionality using following JavaScript APIs:
- Store and serve application resources locally
- Store data locally in a fully-searchable relational database
- Run asynchronous Javascript to improve application responsiveness.
This is Google's project to make their online products such as Reader, Docs and such work offline. Reader is the first of their products to do so. Am looking forward to the ability to do this with Google Docs.