Now given we only had a small preview of things to come [and the fact that it was mentioned] it seems really odd that Outlook is not getting [more of] the new interface. Yes it shows up when creating a new e-mail but by default you get the 'old' standard menu-bar etc. It seems to me Outlook could be considered 'document' centric. I could see the default interface having a band for creating a new e-mail, appointment, task etc. And then logically once you've chosen a type of document then you get an appropriate interface for the document. For example when creating a new appointment it's not difficult to know what parameters people would want to specify for an appointment (start date, end date, etc.) I could imagine this appearing in the area just under the 'tab' bar, in a similar sense to how the new Word interface works, etc.
Since people 'live' in Outlook I'd like to see it get more attention then it's getting. And for it not to get more of the new look and feel through out seems really odd. Also think about the training in the Office suite for these applications. Scenario: "this is how the menu bar works, but for Outlook it's completely different!" ?
P.S. Outlook should also become much more of a PIM, but that's another topic.