Yammer is Twitter for Corporations. The iPhone application from Yammer allows you to view the latest updates from your corporate network and update your own profile.
You start using Yammer using your corporate email address as your identity. Once confirmed and logged in you can post and view updates, post replies and much more. Yammer also supports groups, which has only recently been partially added to parts Twitter.
Update: Yammer 2.0 is out tonight and adds Push notifications, a received tab, cached feeds, landscape mode, camera mode for attaching photos, auto saving, and much more.
This 3rd Party App is available at the Apple iTunes AppStore. Browse the full list of all AppStore apps filed under the AppStore category.