It's a very context-dependent phrase. You could say it when someone asks you to do ten thousand things in one day (basically overwhelming you). In this case, "c'est tout un programme!" means litterally "you've got quite a schedule for me!"

It also often has an ironic connotation. For instance, if someone is describing you is the long list of tasks he has planned to go through or all the museums he has planned to visit during his holidays, you would answer "c'est tout un programme..." because it both looks long and boring and you are happy you are not bound to participate... But as Marc mentioned, this is a lot depending of the context.