Gmail Labs Adds A Preview Pane To Gmail
Google just added a long-desired lab to Gmail: a preview window. Now Gmail can operate in a widesceen-style view similar to Microsoft Outlook and the new Apple Mail. If you like having your messages list available even when viewing, this is a great feature to have. To enable it, just open Gmail, go to Labs, and turning on the Preview Pane option.
New in Labs: Preview Pane [Official Gmail Blog]