wiki recommendation

What do I recommend?

A deployment of JIRA confluence

Arround £10k for unlimited users, both JIRA Confluence running on a 3 moderatly beefy boxs

It is very easy to use.
It is very easy to create a new area for a project or initiative (called a wiki space).
It is easy to control permissions at a space or page level
The team collaboration features such as commenting, bloging and workflow are excellent.
It integrates with enterprise systems such as mail and active directory very well.
It provides an ability ladder for users
simple wysiwyg for you newbies
rich wiki mark-up language for experienced users
macro language for experts
Java plug in API for the hard core nutters who want to change their own features
It has a vast library of mainly free pluggins created the community that prove some really great features
You can export to word, pdf, excel, sharepoint and nearly any format, using the plugins library
It does calendars well
You can create galleries easily
You can have different themed spaces
A real strength is the JIRA integration which allows workflow, task tracking and automation
This has personal spaces and JIRA projects which are a great way to introduce a wiki
This is nearly Open Source, once you purchase you the licence you get source, which you can modify.

The boxes that this runs on can be either windows, solaris or unix, make this decision so that its easier for your support team.
You need three boxes in the confluence clustered architecture
This can be installed in this way in a morning.
Once installed it will need to be skinned, this will not take more than an afternoon
Get a member of the design department to give it a once over

Install it to these domains wiki.atosorigin.com and jira.atosorigin.com
It must be linked to email, this is very easy if you have access to the email administrator
Logging in is a pain, it is easy to add this or the active directory or LDAP
Don't nail it down, try to hold back on securing it so that users can do as much as possible (obviously don't make everyone a member of admins).
Create a Wiki for the wiki, Create a JIRA project for the wiki, users can see and change the guidelines, they can also submit admin requests (using JIRA)
Make the members of the admin group multi-dicipline, have representatives of managers, creatives, network admins, support teams, developers etc ...

When you deploy this you will be adding to the number of different information systems that are available to your collogues,
this can be confusing, you can either
Enforce one system on all your colleges (good luck with this)
or try and bring all the systems together, good search tool will do this, what about one of these
Read this
and this