Well hold down the Option button while clicking on the menu bar items and you’ll be shown more information.
This works for the Air Port icon, the Speakers icon and the Battery icon on the menu bar.
On the Air Port icon, it displays more information about the wireless network the machine is currently connected to. Such as whether it is on a G or N network, the channel, security, retransmit rate and so on.
On the Speakers icon, it shows you a list of available inputs and outputs.
On the Battery icon, you’ll get a display of your battery’s condition.
The condition can be one of the following: Normal, Replace Soon, Replace Now or Service Battery. You can click on the entry itself for a help window with more information about each condition.