When did work become all about fun?
It didn't, but when the organizations figured out that engaged employees are the ones who are enthusiastic about their work and take postive actions to further the orgnization's reputation and interests employee engagement became a hot topic. And when you consider that the engaged employees are more productive, easier to manage, and not to mention more fun to work with, one needs to seriously think about the fun aspect in work as well.
Employee Engagement is about enthusiastic employees, who are working harder and providing you better value, while they are enjoying what they do. It is a win-win situation, that may be tricky to achieve, but well worth the effort.