There are two different types of temporary employees. Those that fullfill a need while you are waiting on the perfect fit, and those that complete a project with a set date. Both have their value, and their place. Both, can surprise you of their value and become permanent. The danger comes from when that person doesn't know that they are temporary. When you treat them like they are full time, yet aren't clear about their future. When they are measured against a metric they aren't aware of.
Are you a temp? Do you know? If so, what kind? Do you have a chance at becoming permanent? Or are you investing your energy into a situation that has a cap on how much you can get in return, no matter how well you do?