This has the potential to be a really long-winded thread. As with cassette tapes, blank CDs, VCRs, and photo-copiers, there is absolutely nothing wrong with file-sharing. The illegality/ethicality (real word?) of depends on what the end-user decides to duplicate/share.

Sharing/copying music is not illegal, assuming you have the authority to do so. Viewing/sharing porn is not illegal in most places, there are exceptions however, such as under-aged participants/viewers.

Is it ethical? It depends on what your morals are. I don't have any problems with pirating music (hmm, I wonder if IP addresses are logged here...I could get in trouble for that comment). I do not approve of under-aged pornography or under-aged viewers. But what am I supposed to do? What you do with technology is your own business, just keep it to yourself and don't expect me to sympathize with you when you get caught.