Not necessarily. At least for writing gigs my wife has done, often they involve assigning all rights but not ownership to the client. This is spelled out in the contract, I imagine to avoid controversy over whether there was "work for hire" or not. On the other hand, every dev job I've taken has had me sign a thing saying that the work I do is work for hire and the employer owns the copyright. Seems fair, they're giving me a paycheck after all.