Judging by the media coverage, the Supreme Court justices know a lot more about file-sharing than the average American parent. As they listened to arguments in the landmark MGM vs. Grokster case yesterday, they peppered both sides with questions about “deep house mashups” (I think this means grabbing tracks from various songs and mashing them up to compose something new with sound-editing software), SiliconValley.com reports. They were looking at whether the P2P networks were a “gigantic [copyright] infringement machine” and should be outlawed as such, as Hollywood argues, or whether – like photocopiers – they could indeed be used for infringement, but that fact alone “would not have allowed book publishers to sue Xerox for violating the copyright laws,” as was ruled in the ’70s, the Los Angeles Times reports. The placards of little protest groups circling outside the Supreme Court yesterday said a lot: One sign read, “Feed a Musician: Download Legally.” Signs for the other side said, “Fight for the Right to Innovate” and “Hands Off My IPOD.” Here’s CNET’s coverage. The Court’s decision is expected in June.