There have been a few Wi-Fi managers for BlackBerry that turned on and off your Wi-Fi connection based on your location but I think Wi-Fi Manager by PingDev is the first free one. Joseph let us know about this app and I have to say it works like a charm. You install it and then set up your location ID’s when you are in the location you want Wi-Fi to be on for and it just works in the background.
NOTE: When you install the app you will NOT see it as an icon on your homescreen. It integrates tightly with the Options/Settings on your BlackBerry. You need to go to the Options and the select Third Party Options (on BB7 Devices) and there you will see the settings screen.
You can pick up Wi-Fi Manager free in App World and let us know how it works for you!