This was a pleasant surprise, a *summary* judgment against Viacom in favour of Google:
Today, the court granted our motion for summary judgment in Viacom’s lawsuit with YouTube. This means that the court has decided that YouTube is protected by the safe harbor of the Digital Millennium Copyright Act (DMCA) against claims of copyright infringement. The decision follows established judicial consensus that online services like YouTube are protected when they work cooperatively with copyright holders to help them manage their rights online.
It would be foolish to imagine it's the end of the story: Viacom is almost certain to appeal. But almost more important than this possibly provisional result is the reasoning of the judge. Basically, he says that you can't start fiddling with the DMCA to suit your own purposes, and that if someone like Google fulfils all the conditions, then they are protected – end of the story. In particular, he writes that [.pdf]:
Mere knowledge of prevalence of such [infringements] is not enough. That is consistent with an area of the law devoted to protection of distinctive individual works, not of libraries. To let knowledge of a generalized practice of infringement in the industry, or of a proclivity of users to post infringing materials, impose responsibility on service providers to discover which of their users' postings infringe a copyright would contravene the structure of operation of the DMCA.
In other words, content owners have to specify precisely which files they claim are infringing. They can't just say: “everyone can see there's infringement on your site, find it and deal with it.” If upheld, that's very good news, because it means that anyone that sets up a mechanism for carrying out DMCA requests doesn't need to go through their entire holdings looking for possibly infringing materials (obviously impossible for a site like YouTube.)
Of course, it depends what the US appeal judges say if it goes to them, but it seems to me that the current judgment makes some very strong points that will be hard to gainsay.