I have to say, I find the ribbon bar a joy to use. there was very small adoption time, and I actually now work faster in office than ever before. This really is (imho) something Microsoft UI team has got exactly right. It's not just the UI but how passes selections back to the application (every option, in word for example, when hovered over is instantly translated onto your document allowing fast previews before making a selection. wonderful stuff.
Also, it's not just a matter of copying as some have said. We should always try to take whats best out there and give it our personal slant. As for licensing, well whats the problem? Yes, I prefer OSource or open spec products (PDF for example), but not every product benefits from this kind of use agreement. And at the end of the day it costs nothing to read the specs and see what can be gained. I have also thought about creating a take on the Ribbon, simply because its such an effective UI. More the principal than the exact implementation is whats important. IMO, if there's a 120 page document discussing the use and ideology behind this UI then I think everyone should read it, if nothing else just to get an insight into what is an effect piece of design. (that goes for all tech documents that we can gain insight and knowledge from) hope that didnt sound like a rant, I just think people should keep an open mind, especially where MS are concerned. It's just to easy to know them (ok, they are hateful agreed, but must get it right every now and then)