UltimateSoundBank have released Plugsound v1.8.7 for OS X, the first official release for OS X, previously only available in beta.
Updates for all Plugsound modules (Volumes 1 to 6 AND Plugsound FREE) are available for free download as VST, AU, MAS & RTAS plugins.
You'll need to be running OS X 10.2.3 or higher to use this.