I don't agree with your argument, Doug. "Different from" implies a difference in function, whereas "different than" implies simply "something else".

Consider: "I want a glass different from that one" vs. "I want a glass different than that one." The first would imply that you want a goblet instead of a tumbler, for example, while the second implies that you simply want a different one, goblet, tumbler, same style, different style, etc. You might make the argument that the correct adjective in the second should be "other" rather than "different".

American Heritage Book of English Usage on the subject