Connor Tomas O'Brien, in a blog post:
Those who believe that the floppy cannot represent saving a document because nobody uses real floppy disks anymore miss an important point: while symbols initially piggyback on the meaning we assigned to a material object in order to stand in for something more abstract, once a symbol is used often enough, the symbol itself is enough to carry meaning, and the material object is no longer important.
O'Brien has an interesting viewpoint on this topic, which has been on a lot of designers' and developers' minds ever since we started debating things like skeuomorphism.