This is big news - there is now a well-designed standardized format for office documents. This is good news for business, as this means documents created today will be readable forever.
In 2004 Microsoft took in $10.8 billion in from “Information Worker” products, of which Office was probably the largest part. Doubtless they will clear another $10 billion or so this year just on inertia (that is one big pile of inertia!).
The standardized document formats mean businesses can drop out of the Microsoft upgrade cycle. Frankly the improvements in Office in the past decade have been relatively minor, and certainly not worth the upgrade costs. What drives businesses to upgrade to new versions is the simple fear that someone might send them a document from a newer version of Office, which they will be unable to read.
The availability of OpenOffice (packaged as StarOffice gets you support from Sun) means that you no longer need to buy Microsoft Office in the first place.
Give the business world a few (or several) years for this to sink in, and you create a 10 billion dollar hole in Microsoft’s revenue. While the reason to buy MS Office has gone away, the stunning thought in all this is that Microsoft is going to collect tens of billions of dollars of revenue, just from business inertia!