Earlier this month, Google had launched the Offline version of their email service, Gmail which was using the google gears as a storage for the inbox. We had also conducted a poll on whether this Offline version of GMail could replace desktop mail clients and not very surprisingly we had 76 % votes for the Offline Version. But the mobile version of Gmail doesn't have any offline capabilities. It’s a shortcoming which Google is already working on to reslove. For this Google is looking at HTML5 which offers a standardized way for the browser to do what the Gears plug-in does today, but without installing the Gears plug-in. Now this would enable the Offline feature to be used over various other platforms which still don`t support Google Gears.
You can see the demo of a private version of Gmail that uses the offline storage tools coming in HTML 5. These tools offer offline access to Gmail through the service's mobile interface on both the iPhone and Android platforms which use HTML 5’s offline capabilities rather than Google Gears which is the company's own homegrown set of tools for offline data syncing and storage.