It’s important, I think, for the Open Source community to recognise that there needs to be a collation of tools to make that one killer app - straying away from the “do one thing and do it well” mentality, sure, but that’s where things seem to be headed. Mediawiki + Unobtrusive Sidenotes + a good WYSIWYG editor + some way to integrate with OpenOffice/KOffice + an email interface for email-to/from-wiki + good RSS Feeds + LDAP/AD Authentication + iCalendar (or some wikiable calendar) + exporting to PDF + whatever else as one package will provide some really stiff competition to Sharepoint, which is only improving in integration with Office with the upcoming 2007 release. You could probably use a bit of AJAX to do a number of the extras. Something like Confluence. Without of course taking Mediawiki too far down the same path as Sharepoint - it’s important that at its core, Mediawiki remains a wiki and not a bastardised spawn-of-wiki-CMS.