San Francisco’s Atom Entertainment is about to be purchased by media giant Viacom, the Wall St. Journal reports. Atom Entertainment is home to Atom Films, a site that highlights short films, and the ShockWave series of game sites.

The price is rumored to be $200 million; Valleywag reported on the WSJ story first. Viacom was rumored yesterday to be interested in purchasing social networking site Bebo, possibly for a staggering sum. Bebo plus Atom under the Viacom umbrella could pose a formidable challenge to MySpace.