We needed an Engineering Intranet. So I created a TWiki and told everyone about it. Slow adoption, but as everyone realised how powerful this tool is, they started using it.

The indicator of success is when someone else contributes more to it than you (the person setting it up).

The hardest part of setting up TWiki, in my opinion, is simplifying the HTML layout of all the various screens. For a system that uses templating, it sure takes editing a lot of different files to get a unified look 'n' feel.