I hope that fancier versions of tabbed toolbars with some style changes like gradient colors, collapsing, etc, are not what MS thinks they can go after. If Open Office adds distinct looking tabbed toolbars I certainly hope MS doesn't attempt to claim ownership
of this concept.
Bottom line is MS is an intimidating enough force, and MS Office market penetration is deep enough, to get most everyone to sign the Office 2007 UI agreement. It has in large part become a me-too affair.
I am no lawyer, but a simple search turns up many things that seem to counter what you are saying. Speaking of "Tabs", Adobe already has that one. By my read, if you make a ribbon bar "virtually identical" to MS's, that could be a patent violation (if they
have one). And, imo, it is different enouph from anything before, that they would win (and the fact they have a million layers). But the point seems mute, because they are giving everyone an out to avoid all the madness.
Wow, I can't believe that I have to sign a seperate legal agreement with MS even when I use design guideline compliant controls from a third party like Dotnetbar. Free agreement or not, intentional or not, this says loud and clear MS self-interests are more
important than it's customers and that we can't be trusted.
What's interesting is that you could get close to the office 2007 ribbon using existing controls available in most all GUI's. The idea that Microsoft somehow now owns tabbed groups of toolbar buttons with the name "ribbon" is silly. I've done tabbed groups
of toolbar image/text buttons numerous times in the past in my own applications. This is NOT a new invention. 3D Studio Max has had tabbed toolbars for a long time. There are some additional frill features that Office 2007 ribbon has, like collapsing, scaling, etc,
but that once again can be quickly added to controls already in the wild. What you won't get easily though, is the exact look and feel of the office 2007 ribbon, but that will probably not be that important in competing products like OpenOffice. There is
no reason why OpenOffice couldn't implement tabbed toolbars with their own look, without being accused of copying the ribbon control, because there was already prior art for tabbed toolbars. I look forward to hearing who it is Microsoft thinks they can prosecute
for doing something similiar, but not "exactly" like the "new" ribbon control. 
> sounds like Microsoft is trying to say "we own anything that looks or feels like a Ribbon" which they can't do
I agree. The ribbon looks and functions alot like a tabbed toolbar, which was clearly implemented prior. MS did not invent this concept, they, as usual, enhanced prior art and then claimed it as their own. On top of that they turn around and discourage others
from doing the same with the ribbon control. In the video they actually talk about not allowing others to "enhance" the Office 2007 controls. Say what? MS can improve upon what others have come up with, but we can't improve upon what MS has came up with?
Do as MS says, not as they do? That sound fair? Not to me.