Even Simpler solution ...
If companies need backward compatibility there are two simple solutions:
1) Upgrade everyone at the same time - if it is a large company this will probably happen anyway with corporate licensing, if it is a small company why bother upgrading anyway - it only adds confusion and extra training costs.
2) If that isn't possible set up every Office 2007 system so that files are saved in a compatible format. You can select that format in preferences and use it every time. Office 2007 supports saving in formats compatible will versions back to 97.
There really isn't an issue if companies have competent support staff install and configure things correctly.
