Today's Wall Street Journal has an excellent section on Technology Innovation. Included in the section is Information Found - And Shared, [registration may be required] about social bookmarking for corporate uses, such as information sharing in project management. It's cited as "a fairly quick way to get a widely distributed client team to be familiar with the company and the industry."
Shel Holz mentions that Niall Cook's startup, Cogenz, aims to bring social bookmarking to the enterprise level and is currently seeking beta testers for industry segments. According to Holz, "Cogenz will offer a secure hosted site for use strictly within a single organization, bringing the benefits of social bookmarking to intranets and other internal networks."