Hi, I heard Microsoft allows use of commercially available Office UI controls, with the exception of competing products, such as a word processor or spreadsheet app, etc.
How true is that?
Also, if it is not true, do you know of any free Ribbon controls?
You should look at Jensen Harris' blog entry about licensing the Office user interface which explains it in great detail. However I believe the relevant point here is:
There's only one limitation: if you are building a program which directly competes with Word, Excel, PowerPoint, Outlook, or Access (the Microsoft applications with the new UI), you can't obtain the royalty-free license.
You can still build a word processor with a ribbon. You just can't use Microsoft's ribbon. There have been ribbon-like interfaces around for a lot longer than Office 2007 (the one that sticks in my mind most is the pallet in C++ Builder: very similar to a ribbon), so they definitely don't own the concept, if that's even possible. I've seen a number of third-party or even open source ribbon controls.
I have seen complaints about the ribbon (regardless of Microsoft claims about hundreds of millions of dollars of research) so I don't think I'll consider it anymore.