The idea of having a class jointly share and contribute to bookmarking sites of interest for a course does seem to be appealing. That the information is moderated, as provided by the curation features, is of value to keep the amount of material manageable and the focus on task. It seems that many web-based services come-and-go or become commercialized and that is a concern. As such, a plugin for a WordPress class blog would be more under the control of the instructor.
A solution that appeals to me is a plug-in for WordPress, Mycurator, which would allow the kind of curation I would see of value in adult education social bookmarking.
An overview of the Mycurator plugin and evaluation:
http://rightmixtech.com/content-curation-mycurator-wordpress/
Social bookmarking with Mycurator review:
https://www.target-info.com/blog/page/5/
Social bookmarking by the participants in an adult education class on Small Business Entrepreneurship can be useful in allowing sharing information from knowledge and research done by the participants in the class. For example, topics like marketing and small business management are presented by the instructor based on their knowledge. Participants in the class have life experiences, read books, and have found information on these topics through their own experiences and research which can be shared through a class blog with the Mycurator plugin. In addition, assignments to the class to research traditional marketing as opposed to modern marketing can be shared through the class blog. Similarly, there are traditional management ideas and modern management ideas which can be researched and shared.