Given the fact that Office 2007 document formats (.docx, .xlsx, .pptx, etc) are entirely XML based, why did Microsoft not build in the ability to store only the 'diff' changes when using the versioning features? We're obviously finding that it's extremely wasteful to store up full copies every time a change is made, and that is the only option with binary formats, but the new formats should be different. I know we can turn off document versioning, but we really do like the feature. Am I missing something here? It seems like that was one of the major draws of changing over to an XML-based document format in the first place. Does anyone make a plug-in that accomplishes this?
They are XML-based but still compressed to ZIP files making them binary as far as SharePoint is concerned. Considering that SharePoint doesn't recognise the Office 2007 formats unless you configure them yourself or install the Microsoft Filter Pack, it looks like this feature wasn't ready for SharePoint 2007 RTM.