At Dreamforce, Salesforce highlighted a landmark use case for Slack. It is called case swarming, and it plays to the tool's unique strength to very fluidly create channels and gather ad hoc teams to solve specific issues. Here the case in point (pun intended) is a support ticket, and Slack is the platform where different stakeholders (support reps, product managers, operations, for example) can provide their unique perspectives to reach a satisfactory conclusion faster.
I would like to read more about swarming. And I find intriguing how it can interplay with the principles of knowledge-centered service. In one of my previous projects, I architected an integration between Jira and Salesforce to make sure support and developers communicate in the same terms, each side from their own tools. With swarming, the need for such an integration evaporates quickly.