Microsoft and Sun Microsystems have come a long way since their bitter split over Java in the late 1990s, but until now, Microsoft has never been on the at Sun's annual developer conference.

Microsoft's vice president of strategic and emerging business development Dan'l Lewin will speak on June 4, providing an update on Sun and Microsoft's effort to make Java interoperate with Microsoft's .NET programming environment.

The two compnaies have been on friendlier terms since they settled a lawsuit over Microsoft's use of Java in 2004. And Microsoft has attended JavaOne in recent years.

Microsoft has been working to shed its image as a go-it-alone monopolist in recent years as it struggles to compete in a world increasingly dominated by Internet companies such as Google.

In a statement, Microsoft said its customers need more openness. "We continue to intensify our efforts in several areas, as evidenced by our recent agreement to use the SAML federation standard in both the Sun OpenSSO Enterprise federation solution and the forthcoming Microsoft “Geneva” Server federation solution," Microsoft said.