There are two interesting and related items I've run across recently. One is the growing opinion that BitTorrent has the vast majority of SNIUs of any piece of software out there, and they're probably right, at least from what I can find. See, for instance, http://techlawadvisor.com/induce/2005/03/because-of-programs-like-bit-torrent.html , which argues that the result of Grokster may very well be more INDUCE-like proposals (INDUCE wanted to make it illegal to induce infringement via services like Grokster, even if the court case goes their way). But, barring any INDUCE-like options or Grokster, the recourse left will be to go after the people actually doing the infringing, which is where the second item comes in:
http://whirlpool.net.au/article.cfm/1459
Some Australian BitTorrent site operators are closing down in response to the raid of one provider. This is interesting for a few reasons. First, it's BitTorrent, which, as I mentioned above, appears to be immune to Groksteresque lawsuits (it was also not written by a corporation, and thus there's not really anyone to sue, and it's open source, so no matter who they sued, the software could continue to be developed). This would seem to hint that my general guess--that a decision affirming Grokster would lead to an increase in the campaign against individual sharers. Second, BitTorrent networks are more centralized than those in Grokster et al., requiring a central server called a tracker. This tracker is what makes BT ultimately more sueable in a hypothetical post-Grokster world, as fewer end-users have to be sued. It remains to be seen whether the trackers will be vulnerable to a legal attack. In the US such cases have only ended in settlements, not in decisions.

--Ari