I like the soap opera analogy -- hadn't thought of that. But keep in mind that actors (and other folks that work in long-running shows) will still take other jobs as at the same time as their main gig -- e.g taking a part in a movie in between seasons. That sometimes happens with programming contractors as well, but from what I've seen its far more rare.

Ultimately I agree with the other responder that Hollywood agents are better thought of as deal makers/negotiators than job finders so maybe what limits it from showing up in the software contracting world (and other parts of the film world) is that contract terms are much more standardized so not as much time is needed for negotiation and thus the programmers can do it themselves.