After years of reasonable interoperability and compatibility, Microsoft has released Office 2007, which uses very different file formats:
- Word documents are now .docx files
- Excel documents are now .xlsx files
- PowerPoint documents are now .pptx files
The “X” at the end of these filename extensions stands for “Microsoft Office Open XML Formats”, but they're not terribly open — for starters, they're not stored as plain text XML, but in some proprietary binary format.
If you're running Office 2003 for Windows, you can download a compatibility pack that makes it possible to open Office 2007 docs. The Mac Business Unit of Microsoft has promised some kind of conversion utility, but there's no word on when that will see release. Over at Tucows, we're still on Office 2000 for Windows and Office for Mac, and I suspect a number of businesses are in similar situations.
Given that there are fewer and fewer reasons to upgrade — c'mon, how much more can you pack into a word processor? — I can't imagine business making the switch until absolutely necessary.