I think they mean "OpenOffice.org" when they say "OpenOffice."
They are going to collaborate on "Windows and Linux Interoperability and Support," "OpenOffice and MS Office Interoperability and Support" and "OpenDocument and Open XML Interoperability and Support."
But many people questions, "How do they do?"
Let us go to their FAQ and find an answer.
FAQ from Novell and FAQ from Microsoft
Q. How will the technical cooperation work?
Document Format Compatibility. Microsoft and Novell have been focusing on ways to improve interoperability between office productivity applications. The two companies will now work together on ways for OpenOffice and Microsoft Office users to best share documents and both will take steps to make translators available to improve interoperability between Open XML and OpenDocument Formats.
Q: What does the patent agreement cover with regard to Mono and OpenOffice?
Yes, under the patent agreement, customers will receive coverage for Mono, Samba, and OpenOffice as well as .NET and Windows Server. All of these technologies will be improved upon during the five years of the agreement and there are some limits on the coverage that would be provided for future technologies added to these offerings. The collaboration framework we have put in place allows us to work on complex subjects such as this where intellectual property and innovation are important parts of the conversation.
Have you gotten an answer to your question?