twitter is not inherently credible, but it enables interaction that leads to credibility. a conversation does not confer good faith by its existence. it is the first step toward a relationship. linkedin, on the other hand, presumes relationships between connections. the linkedin connection does (or should) confer good faith from the moment the invitation is accepted.
since last fall, linkedin has introduced several changes to how users see and work with the site. I go through the changes and explain why they matter.