Some time ago, Think Secret had some screenshots up (actually I think that Mac World also had some screenshots in an issue some months back). I have to admit that it looks really slick. I've been really anxious for iWork '08 (I love Pages, but would like a little more functionality, and I really am looking forward to its spreadsheet app), but looking at the completely redesigned interface in Office 2008, I may just end up sticking with it!
(It helps working in Redmond where I have several friends who can pick up a copy of Office at the MSFT store for less money than I'll pay for iWork)