One of the most common conversation points during SharePoint presales is the double barreled desire from potential clients to have an Information Architecture that reflects the organisation's policies and/or process while at the same time "fixing" the UI. Now ignoring the fact that most cannot articulate what that means in tangible terms, the two are joined at the hip.
Over on the SharePoint Team blog, the folks from Provoke have posted a must read "How we did it" entry on the implementation for the New Zealand Ministry of Transport.
Microsoft SharePoint Products and Technologies Team Blog
How We Did It - Tag Driven Information Architecture using MOSS 2007 for the New Zealand Ministry of Transport
If you are SharePoint consultant, you *must* read this article, so go check it out.