Social media changes the conditions for user participation in service development. Active user communities, fast paced iterative development, considerable development after market launch, developer access to users' digital trails, peer production, and low cost feature distribution are well known facets that bring substantial changes. In this paper we distil lessons for participatory designers from an in-depth case study of an over decade-long service development in industry, Habbo Hotel by Sulake Corporation. We argue that the range of core issues that shape user participation in social media can be captured by three interrelated issues: 1) shifts in developer--user social distance, 2) cumulated user knowledge beyond one project, and 3) user-generated content and user-owned services. We then consider what insight these provide for a design initiative we are involved in: the Finnish national public service broadcasting company's teacher resource.