I would endorse taking a sector-by-sector approach. In the U.K., we have established sector panels to be the focal point for this conversation between the departments who have the data and their agencies, and the industry working to provide services in that area. To provide the voice of business and the users of data to government as a whole, we have also established an open data user group. There are more details as to how that operates online.
On April 10th, 2014. See this statement in context.