That link and Joel seem to agree. By default the contractor owns the IP, unless the contract contains the legal phrase "work made for hire." Maybe you should have kept reading?
A “work made for hire” is—
(1) a work prepared by an employee within the scope of his or her employment; or
(2) a work specially ordered or commissioned for use as a contribution to a collective work, as a part of a motion picture or other audiovisual work, as a translation, as a supplementary work, as a compilation, as an instructional text, as a test, as answer material for a test, or as an atlas, if the parties expressly agree in a written instrument signed by them that the work shall be considered a work made for hire.
I think I was probably misremembering my experience as a software contractor, in that I don't think I ever signed a single contract that did not include the "work for hire" stipulation.