What that holds for the future, only "time will tell," said Schwartz, adding, "this is really a comprehensive relationship."

"All the customers are demanding more flexibility and interoperability -- that's also a strong argument for us to work together," said Otellini.

The vendors will also synchronize releases around chip and operating system upgrades. "We want Solaris to absolutely scream on Xeon," said Schwartz.

Sun's historic hardware focus has been on its UltraSparc line of servers. That began to change in 2003, when the company announced plans to sell x86 servers based on processors from Advanced Micro Devices Inc. In 2004, Sun settled antitrust battles with Microsoft Corp., and the settlement agreement included a pledge by both vendors to improve system platform interoperability.

Sun has faced longstanding pressure to offer x86-based servers because of decisions made by customers such as Don McPhee, director of technical services for Atlantic Blue Cross Care in Moncton, New Brunswick.