Those wondering what this year's surprise deal between Microsoft and Sun will actually produce should get an update in coming weeks, when the companies detail some of their interoperability work in areas like Web services, directory services and security.

Top executives from both companies will host a press conference and webcast in late December or early January as part of a month-long interoperability webcast series put on by Microsoft, according to Sun marketing director Emmanuel Obadia.

The update, coming some eight months after the two companies jolted industry watchers by declaring a legal cease-fire and entering a collaboration accord, will be the first formal briefing on the fruits of their labour.

.Net and Java interoperability, Web services, and directory services integration will be highlighted topics, Obadia said during a recent interview in London. Sun customers should also expect to see "better integration with the Microsoft stack in terms of collaboration and communication," Obadia said.

Sun CEO Scott McNealy has already pointed to interoperability and single sign-on capabilities between Microsoft's Active Directory and Sun's Java System Identity Server, and Java and .Net compatibility as examples of the collaboration.

More interesting, perhaps, is how far the alliance goes, and whether their work will make a significant difference to customers, said Ovum research director Neil Macehiter. He wondered if the .Net and Java collaboration will go beyond the companies' own work in Web services and provide interoperability to include other Java product vendors, for example.

RedMonk analyst James Governor predicted that broad interoperability based on standards would be unlikely, however, and said that the alliance is aimed at providing direct compatibility between Sun and Microsoft products. "This is a joint go-to-market play," Governor said.

One ambiguity appears to be file format compatibility, such as letting users of OpenOffice and Sun's StarOffice import Microsoft Office documents. Obadia seemed to suggested that it is an area where the companies have not made much progress. "Office documents are an area where work needs to be done," Obadia said.

While it benefits Sun to offer its customers Microsoft Office compatibility, there's not much incentive for Microsoft, Macehiter said. As the companies continue to hammer out the full extent of their collaboration, for now customers can at least look forward to the details on some coming benefits.