says SCOTUSblog -- not what I would have predicted. (I wasn't sure about the bottom line, but I expected at least some votes in favor of Grokster.)
This ruling seems to shift the burden of copyright enforcement from courts to inventors, which is very inefficient in terms of allocation. I think software developers by and large are not experts on copyright law. In order to comply with this ruling, developers will have to educate themselves in copyright law, or hire an expert. Both of these options are expensive. This ruling creates disincentives for developers to solve data transfer problems on the Internet, with no corresponding creativity incentives elsewhere.