The Wireless Today Screen panel is a quite recent addition to Windows Mobile's armoury and although it doesn't do a lot, what it does do is useful, which is why I think its a shame that it isn't enabled by default on most devices.
When enabled the Wireless panel displays the state and connection of your phone's wireless radios. For example the mobile network operator, the SSID of the wifi point to which you are currently connected and the state of your Bluetooth radio.
Useful stuff, but not really worthy of a Today Screen slot of its own. However as a click, tap or button press on this panel gives you direct access to the Wireless Manager its worth keeping enabled if you, like me, are constantly required to switch into flight mode and out again. Some devices have a dedicated hardware button for accessing the Wireless Manager. You may find that the Today Screen panel is still useful to free that button for another purpose.