The default Location as defined by Apple is called "Automatic" and includes settings for all the communication devices on my Powerbook (Modem, IR Port, Ethernet and Airport). However, I seldom need a connection to all 4 devices simultaneously (OS X can handle this and assign an IP address to each connection apparently) and really only use one connection at a time.
If you turn off unused devices, your laptop will power them down thus saving battery life. So creating separate Location profiles makes sense for the Laptop user trying to squeeze some more time out of the battery. To create additional Location Profiles:
- Open Network Preferences in System Preferences.
- Choose "New Location" under the Location dropdown menu selector.
- Give your new Location a name, ie. "Airport Only".
- A new Location will be created with all available devices present. Choose the "Network Ports Configuraion" under the Show drop down menu.
- Deselect all the other devices except the Airport.

