The icon column in Gmail helps to easily distinguish the various types of items in your inbox (e.g. messages with attachments, chats, calendar invitations, Buzz posts, and more). It's usually all the way over on the right of the screen, but with screen sizes becoming increasingly wider, I chose to make a very modest addition to Gmail Labs to try and give these icons greater visibility.
I found it much more useful to have this column situated on the far left of my inbox -- and it turns out that many of my colleagues did too.
If you'd like try out "Move Icon Column," simply visit the Labs tab under Gmail Settings, find this new Lab in the list, hit enable, and then save. It's not big and it's not clever but hopefully this lab might just be helpful for you too; it's the little things in life after all.
Source : http://gmailblog.blogspot.com/2010/05/new-in-labs-move-attachment-and-other.html