> and that maintaining the look-and-feel of the OS should be very important.
I don't think maintaining the look-and-feel of the OS is very important. In fact I would go so far as to say that attempting to shoe horn novel interface requirements into local OS look-and-feel requirements is a detriment to interfaces.
A bad interface is a bad interface no matter what. Same goes for a good interface.
But I think that if you look around at most of the most successful pieces of software across all platforms (by pure volume), very few of them look anything like the prevailing look-and-feel guidelines for their host platform -- I'm talking about Office, Photoshop, Firefox, Chrome, iTunes, GarageBand, iLife...
iWork at least looks like a piece of software that conforms to the look-and-feel rules.
But then we get something like Aperture 3 which could be something running on just about any platform.
Most of the top iPhone apps could be running on anything with a big touch screen (and some of them are almost pixel identical across platforms): Pandora, Remote, Yelp, New York Times, Jott, Netflix, Shazam, etc.
People care about app consistency across platforms not local consistency with the OS.
Web apps blow the idea of local OS consistency out of the water. I won't even list million user web apps because we all know what those look like, and they pretty much look the same no matter the platform. Sites that try to "look like" some OS, end up looking rather silly to be perfectly honest.
No, maintaining the look-and-feel of the OS is not anywhere near the top of pretty much anybody's priority list these days.