I was recently demoing the Office 2007 clients and talking about all the new innovations in this release; one in particular was the Quick Access Toolbar that presents itself in Ribbon enabled applications (for all there is to know about the Ribbon see Jensens blog). The QAT looks like this:
 
It's that section to the right of the Office Menu above the Home tab. A user can manually add extra regularly used buttons or Groups to this area to allow quick access if using the tabs is too many clicks for a particular command. The QAT can also be configured to be located below the Ribbon. See Jensens blog.
During this demo the customer asks:
 
"Can the QAT be customised and standardised across the enterprise?"
    
Great question, shame we didn't have an answer for it on the spot. Surprised no one has asked before actually. Sure I assumed we allowed this in some way and I guessed it would be through XML but was not absolutely sure where or how the customisation could be made. As it turns out the QAT can be customised per Ribbon application/per user or per document.
 
This means you could deploy Office with a standard set of QAT buttons and groups across the company or simply target certain templates across the organisation.
 
This is where you will find per application/per user QAT customisations for a particular user and you could target the All Users profile to affect all users of the PC:
 
 
Here you can see the packaged customisations when made to a particular document or template; this is the DOCX package extracted.
 
The customisation creates a UserCustomization folder in the package. This contains a CustomUI.xml file with the associated changes.
 
 
 
So once you have some understanding of the structure of the XML used for ribbon definition you can create your own document or application scoped customisations to the QAT. Of course there is a growing number of tools on OpenXMLDeveloper.org to help you generate and validate this XML like the CustomUI Editor Tool.