Digital media may have lost much of its ghost-in-the-machine wonder now that we carry the web in our pockets and incorporate these technologies into most everyday activities, but the group show Dark Matters: Artists See the Impossible, at San Francisco's Yerba Buena Center for the Arts through November 11, allows the media work in the exhibition to reassert some of the lost conceptual heft of its material. The centerpiece of the exhibition is Ben Rubin and Mark Hansen's collaboration Listening Post, a celebrated work that trolls the web and pulls snippets of text from message boards and public chat rooms. It displays the fruits of its scanning on a curved arrangement of small LED displays and articulates a few of them with a cold, synthesized voice. Situated among photography, video, and object-based conceptual work that all points to the (frequently sinister) unimaginable, Listening Post's wash of jumbled information not only surveys the singular preoccupations--from politics to porn--of the users who typed it, but also suggests a control-room window onto the unfathomable vastness of collective production. It is a staggeringly occult--or even spiritual--representation of the Web.