What is the current state of the law on opinion versus fact?

Until a few years ago, we drew a sharp, formalistic line between fact and opinion, holding that anything cast in the form of an opinion was absolutely protected by the First Amendment and could not serve as the basis for a defamation claim. See, e.g., Ault v. Hustler Magazine, Inc., 860 F.2d 877, 880-81 (9th Cir.1988), cert. denied, 489 U.S. 1080, 109 S.Ct. 1532, 103 L.Ed.2d 837 (1989).