Google's new Gmail mobile web app sports offline message caching,

[wraggster]

If you've been losing sleep in eager anticipation of the new Gmail for mobile, rest assured that you'll sleep soundly tonight. With support for both Android phones and iPhone / iPod Touch OS 2.2.1, the gang over at the Google mobile blog are justifiably proud of the new app. Expect nothing less than a more robust cache that utilizes Gears (for Android) and SQLite databases (for iPhones / touches) to allow you to compose messages and access recently read messages without a network connection, an improved look and feel, and the all new "floaty bar" (their name, not ours) that keeps popular menu commands from scrolling off screen, as this bad boy rolls out progressively over the course of the day. Most interestingly, using the new Gmail on your devices doesn't require any tweaks or installs -- it's utilizing HTML5 (and its offline storage APIs) already present in the browser. Google is just turning on the juice behind the scenes. And for those of you who are resistant to change, fear not -- the previous version is still available

http://www.engadget.com/2009/04/07/googles-new-gmail-app-sports-offline-message-caching-lots-of-f/