I have not yet completed reading through today's two Supreme Court opinions (over 100 pages, and I'm a fairly slow reader...) but what I have read so far is disappointing. While there's no way to accurately predict how great the impact will be on the number of copyright lawsuits filed (EFF says the opinion "will fuel a new generation of entertainment industry lawsuits against technology companies"), I think it's fair to say that technology makers will now face even greater uncertainty and risks in the copyright field. Under the Court's 9-0 opinion, content owners may now bring lawsuits againts technology makers on theories of secondarily liable (inducement) for the copyright infringement of third parties (e.g., their users). Because of the fact-specific nature of the Court's ruling, lawsuits raising this new inducement theory will likely lead to expensive and protracted litigation. Discovery, already a huge cost to litigants, will open up to explore new fact questions that lawyers will undoubtedly pursue with zeal on their clients' behalf. (If I were more cynical, I could call this the full-employement decision for copyright lawyers.)
Unfortunately, much like the fair use doctrine of copyright law, I can imagine that those entities and individuals faced with fighting an unfounded Grokster-based claim, will often lack the funds to take on the larger, corporate-funded, content-owner Plaintiffs. To escape the risk of lawsuits, such innovators will go underground and some may simply give up their innovative pursuits all together. That is a potentially devastating result for all involved.
Links to the Grokster opinions (separated by majority and concurring) are available from Joe Gratz. Brand X is available from here.