Google launched GOOGLE GEARS, a browser plug-in that will let people run Web applications when they’re connected to the Internet or not. The main aim of Google Gears is to create a single, standardized way to add offline capabilities to Web applications.
Gear has three components–a local Web server which runs in the browser, the open-source database SQLite for storage, and browser extensions that allow multiple JavaScript jobs to run in parallel.The initial code is for JavaScript developers who write Ajax-style Web Applications.It is compatible with Internet Explorer on Windows; Firefox on Windows, Mac OS and Linux; and on the Safari Mac OS browser.

Check this link for more details:  http://news.cnet.com/Google-kicks-offline-Web-apps-into-gear/2100-7345_3-6187596.html?tag=lia;rcol