I need to make the phone available for all people in a building, for example. If someone were to try to walk outside of the building with the phone, the phone would shut down or a loud alarm would sound. Any thoughts?
I don't think you can set the phone to shut itself down based on this, but you could definitely make it play a loud sound, or even send an SMS message or a voice call to a particular number.
Matt H's answer in conjunction with Prey might be useful for you.
Have Tasker send an E-mail when the phone leaves the building. You read the E-mail and mark the phone as "stolen" in Prey. Prey gives you a lot of options about how you want your phone to react to being marked as stolen. You can lock it down and force the GPS to stay active as long as the battery isn't dead, letting you know where the device is.
Yay for daisychaining answers, btw.