The idea is that minimal class and package documentation should be with the classes themselves, the rest whould be in a wiki.
Your wiki is where you can build the dense network of relationships that truly document your software. If your code is related SNMP, that can be a link to SNMP, for example. You can refer to the product specs or design docs that relate to the software. You can refer to a talk about alternate strategies that weren't taken.
Your wiki is where you can easily write larger pieces of example code.
No... not sure wikis are actually useful or read. Except for this wiki of course. The time I spent creating a table specing out the development servers and whats on them could easily have been spent drawing them in a notebook, because anyone only asks me ad hoc questions anyway, they dont read it, no matter how many times I point them to it.
Wards wiki is great and worthwhile, but I dont know what kind of a wiki it is, its an enduring forum, not a project documentary repository. Documentation is worse than worthless, its lies. The docs used by management are nothing more than glorified forms of the scraps of papers I write my notes and cheats and recipes down on to get my tasks done.