After all that speculation, Gmail is finally available offline and works pretty much the same way other Google products work. You’ll need to have Google Gears installed and this is an Labs feature unlike with other Google products.

After enabling this feature even if you’re offline, you can open your web browser, go to gmail.com, and get to your mail just like you’re used to.

Once you turn on this feature, Gmail uses Gears to download a local cache of your mail. As long as you’re connected to the network, that cache is synchronized with Gmail’s servers. When you lose your connection, Gmail automatically switches to offline mode, and uses the data stored on your computer’s hard drive instead of the information sent across the network. You can read messages, star and label them, and do all of the things you’re used to doing while reading your webmail online. Any messages you send while offline will be placed in your outbox and automatically sent the next time Gmail detects a connection. And if you’re on an unreliable or slow connection (like when you’re “borrowing” your neighbor’s wireless), you can choose to use “flaky connection mode,” which is somewhere in between: it uses the local cache as if you were disconnected, but still synchronizes your mail with the server in the background.

Gmail offline is available (sadly) only for Gmail users in US and UK only, hopefully it will be available for everyone else.

To get started:

1. Click Settings and click the Labs tab.
2. Select Enable next to Offline Gmail.
3. Click Save Changes.
4. After your browser reloads, you’ll see a new “Offline^0.1” link in the upper righthand corner of your account, next to your username. Click this link to start the offline set up process and download Gears if you don’t already have it.

[via Official Gmail Blog]