I agree with jane. Write to the personnel department, or the head of the department that's advertising the job, and ask them to take into consideration your time there. Tell them what a great place it is to work for, and that you'd love to be given the opportunity to prove yourself, by hopefully being given a permanent position. If you don't make it, at least console yourself with the fact that you were in the running and managed to get to the last two. Best of luck.