I had to laugh when I read the announcement that Sun were going to provide a couple of developers to work on the Mac version of OpenOffice, which basically is a dire X11.app that no Mac user in their right minds would want to use.
So, they're getting people who have never developed a Mac application before to make it feel more Mac-like? I mean, do these guys really have a clue? Apparently not: in a question-and-answer comment, Lars asked "How're you doing the port? Using Cocoa or Carbon?" to which PhilippL replied "Currently the plan is to use Carbon." Oh dear. Granted, if you read the Porting Overview at Apple's developer connection, it does say:
Mac OS X supports multiple application environments for developing and porting your applications, including Cocoa, Carbon, Java, and BSD. Cocoa is the best choice when developing a new application; Carbon for porting a Windows-based application or one already implemented in C or C++; BSD for command-line tools and other UNIX programs; and Java for existing Java applications.
Several apps on the Mac do use Carbon – Eclipse is an obvious one – but Carbon is very much the old-style compatibility layer for Mac OS 9 and prior systems. All of the Apple apps (with the possible exceptions of Finder and possibly QuickTime) are Cocoa based; and a lot of the functionality-for-free (dictionary, printing, other services e.g. pipe to grep etc.) you get only with Cocoa.
That being said, there's some issues; a system which builds its own app dynamically is probably more difficult than normal for Cocoa, and it's not like the app doesn't have some of this stuff already.
But the biggest concern of all is that even if the widgets are natively rendered, and boots up as a proper Mac app (rather than X11 emulation), there's still a difference between a UI that's been developed for a Mac, and that which has just been ported from other systems. In short, it doesn't just have to look Mac, it has to feel Mac too. I really doubt that any engineer who knows nothing of the Mac will succeed in that goal; even Microsoft knows this, which is why the MS Word etc. interfaces differ on both Windows and Mac platforms; they're targeted to their set of users.
Will the new MacOffice look like a proper Mac application? Will it even exist, unlike the other times when the same idea has been promised? Only time will tell.