The Notification Area on the taskbar has undergone some minor changes in Windows 7. Gone is the ability to expand the Notification Area laterally to view hidden icons. Clicking on the 'Show hidden icons' button will now open up a separate little window just above the taskbar:
[attachment=2:2w7vu4jx]show hidden icons.png[/attachment:2w7vu4jx]

Windows 7 will hide icons by default but it is a simple process for the user to choose whether to hide an icon or display it permanently in the Notification Area.

Here