I believe Microsoft is really committed to promote interoperability with other vendors, even when they are direct competitors. Recently announcement on inclusion of ODF and PDF support into Office 2007 Service Pack 2 is a strong evidence.

Having said that, the above mentioned 2 document formats have already been supported via freely available addins

1. PDF Save as in Office 2007
2. ODF translator for Office 2007

The default and newer MS Office file format still has its own advantage over the others especially for integration works with line of business applications. So after acceptance by ISO, Microsoft will of course continue to work on this format for the benefits of its customers.

Another interoperability evidence would be support of Silverlight inside Linux by Novel, which I think is very cool.