Microsoft Office 12 Reinvents the Office Productivity Suite: "So Microsoft took the bold and unanticipated step of completely overhauling the Office user interface. What's astonishing, of course, is that no one saw it coming, not competitors, not analysts, and not users. Over the past few Office updates, Microsoft has made baby steps towards improving the Office interface, adding small features like task panes and smart tags that bubble up previously hidden functionality. But competitors such as OpenOffice.org and Sun Star Office were busy copying the last Office interface, Microsoft was busy hatching something new."
See the full post for more details. I agree with Paul Thurrott's assessment and look forward to exploring Office 12.