Presentation at Open World Forum 2011. Abstract: This talk makes the case that (1) a vibrant commons of knowledge (culture, science, etc) is required for other 'opens' (source, infrastructure, society) to survive; (2) knowledge is harder and slower to open than other layers; (3) it can be done anyway, through disruptive services and collaboration that creates new categories of knowledge works rather than merely recapitulating and failing to compete with existing proprietary-dominated categories. Understand the threat, challenge, and resultant opportunities for entrepreneurs, policymakers, and activists to contribute to ensuring an open future.