I was watching one of those investigative specials on music piracy a while back, and they concluded by saying that given how things stood today, it was probably inevitable that music would one day be completely free to everyone. That makes me wonder about RPG PDF files also...though quite obviously that'd seriously hurt the small PDF publishers if they couldn't release products for pay anymore, so that's probably not realistic.
Likewise, has anyone thought of possibly combating file-sharing programs by release bogus files with the names of their products onto them? I heard that some music companies are doing this, uploading MP3 files, with the file names listing them as popular songs, while the actual file is blank. The people who just leech files and then turn around and spread them around don't listen to them to find out the difference, and pretty soon people just stop trying after they've downloaded bogus files a few times.
Public service announcement: Don't steal RPG products. Become a reviewer, and they'll give them to you for free.