[ILUG] SharePoint killers?

[Paul Reilly]

Hello,

I'm looking for a good open-source Wiki software package which I can
run on Linux. The company I am sourcing this for has been using SharePoint
up to now, but they are not happy with it. So I'm looking for a sharepoint
killer app, which shouldn't be too hard, since IMHO sharepoint is a
load of *&^%^.

The end-user base are not very techy, so learning wiki-speak is out.
It must:

- have WYSIWYG  editor
- be able to authenticate users to AD, or LDAP
- have nice features, like export to PDF etc.
- have search functionality
- support document storage
- would be fantastic if you could do 'tag' ing of pages/documents,
  and have a tag-cloud

Confluence is really nice - see here:

http://www.atlassian.com/software/confluence/

but it's not open-source, and is a bit pricey.
Has anyone found a good wiki software package which works for
non techy people in an AD environment?

Paul