I was not much surprised to see this Lab update from Gmail as my expectations from Google has always been high. A new feature called “Unread Message Icon” has been introduced in Gmail Labs. If you have always been that neat and clean with your Gmail inbox, then keeping a close watch on the number of Unread emails must be crucial for you.
This is even easy if you just see the title of your Gmail tab, however just turns difficult when a lot of tabs are already opened simultaneously in your browser window.
As a solution to this situation, a lab feature Unread Message Icon is introduced which will let you see the number of unread emails in your inbox directly as an icon appearing on your Gmail’s tab title bar. If you see the icon in the above image, it clearly displays the number of unread emails in your Inbox (please don’t peek in a lot as that inbox is mine 
).
At present, this lab feature shall work only in Chrome (version 6 & above) and Firefox (version 2 & above). However I believe Google should not take much time bringing in the feature of our IE users as well. Do comment on this post and let me know if you feel this lab update is going to be useful for you or not! If you have any questions or suggestions as well, do let me know.