The Chatter Dev Zone (part of the Chatter Developer Preview, which is now open) is a shared environment that lets developers explore Chatter, use Chatter with other users to get a feel for it in action, and view the source code of apps built on Chatter.

We’ve just enabled Mobile use in the Chatter Dev Zone! If you install Salesforce Mobile from the App Store or App World, or go to http://mobile.salesforce.com with your device, you will be able to then access your Chatter feed, leave comments and so on.

Here’s what I find when I visit with my iPhone: