While preparing for my Tuesday demonstration of XML features in Office 2003 I found out that Word XML namespace changed from: http://schemas.microsoft.com/office/word/2003/2/wordml to http://schemas.microsoft.com/office/word/2003/wordml.
It's not that I'm opposed to changing beta-time namespaces but all my documents, saved in Office 2003 beta2 as XML, won't open up properly in Office 2003 RTM. I have to change them by hand.
Another thing that pops a question is: What if Microsoft releases two Word versions within a year that need different namespaces? That has not happened yet, but this kind of namespace naming convention is not as flexible as a standard year/month, W3C like one.
Changing the namespace to http://schemas.microsoft.com/office/word/2003/10/wordml would break things too, but wouldn't brake the convention.
Conventions, especially namespace declarations, carry a semantic meaning and one should avoid breaking them.