Connect the two great products and reduce the silo
Any corp that is using alot of Confluence and SharePoint needs this - to break up the internal wars of which product is better, and to share the wealth of info. That alone pays for itself - seriously, aside from the real work that also is better enabled.
They are both great prods, but they are not both equal products. Share the strengths of both with integrating them - it is that simple.
If you have JIRA too, it also makes sense to break the silo one more level with the JIRA to SharePoint Connector by CustomWare.