Three Cheers for Commenter BruceM,

whose comment was cited in a Fourth Circuit appellate brief a few months ago. It's in the Reply Brief of Plaintiff-Appellant Christopher Scott Emmett, filed by the Virginia Capital Representation Resource Center in Emmett v. Johnson, 2008 WL 345230, *5 n.5 (4th Cir. Jan. 11):

Since the grant of certiorari in Baze, some commentators have suggested that other controlled substances could be used in lieu of a barbiturate to cause painless death. See, e.g., The Interesting Case of Baze v. Rees, http://volokh.com, archived entry posted 12/31/2007 at 1:09 a.m., comment #8 by BruceM (speaking, with some apparent authority, in favor of using potent opioid to accomplish lethal injection).

A quick search also noted that I quoted a comment by James Fulford in my Washington U. L. Rev. piece on Scholarship, Blogging, and Tradeoffs: On Discovering, Disseminating, and Doing, and Larry E. Ribstein quoted a comment by Marty Lederman (a prominent lawyer, and now a prominent blogger, in his own right) in his piece in the same symposium, on The Public Face of Scholarship. But this is the first comment cite I've seen in the briefs, and I've seen none in court cases. If you can find other such cites — again, not to blog posts as such but to comments, preferably by people who aren't themselves noted scholars, lawyers, or bloggers — please note them in the comments below.