I have a scenario that I'm trying to work through and would appreciate your thoughts...
Imagine you have a corporate intranet with about 50k pages and a really outdated information architecture. You want to put a new (task focused) IA in place and install a new CMS with improved templates and publishing workflow, but any changes to content are out of scope. There will be no content migration and the intranet site must be fully functional throughout.
How do you improve the IA and add new CMS functionality to an existing site without throwing away or migrating thousands of pages of existing content?
EDIT: Thanks for your great comments so far... As Rob says, this is not a new problem and I'm sure that organisations don't slash and burn their old intranets before replacing them with new shiny portals, intranets and wikis.