Over the next few days Google will roll out the Gmail offline feature. Using Google Gears, Gmail will continuously keep a cache of e-mail messages stored locally on your computer so that when you go offline, you still get access to it. The video below shows how it works.
As is suggested all of the features in Gmail will continue working while you’re offline, including search. I wonder, does it cache all of your e-mail locally? That seems like an awful lot of information.
The feature will be available as part of Google Labs (go to Settings > Labs) for users using US or UK English as their language on Gmail. In addition, of course, you need to have Google Gears installed. Google Gears is available as a Firefox, IE and Safari extension and is part of Google Chrome by default.
Update: on the storage issue, on Venture Beat: