In Windows 7, I sometimes see this "sun" icon overlay in the networking tray icon:
What does it mean?
Bonus points: cite docs.
It means that wireless networks are available. But you have yet to connect to one.
Screenshot of video overlay in the URL above:
It means you are not connected to any wireless network.
http://windows.microsoft.com/en-us/windows7/View-and-connect-to-available-wireless-networks