Details of the Grokster argument
Timothy K. Armstrong sat in and has a long post detailing the argument. SCOTUSblog also has good info, including:
Several members of the Court — but especially Justices Antonin Scalia, Stephen G. Breyer and David H. Souter — seemed troubled about the potential impact of a tightening of copyright law on small inventors — “the guy in the garage,” as Souter put it.
Breyer wondered whether a lawyer for a developer — for example, the inventor of the iPod — could assure his client that he could continue to develop new products without fear of being held liable for the illegal uses to which the products might be used by some.
Finally, Copyfight has a few more links to commentary.
UPDATE: Yet more details from CNN/Money.