That's because Gates has for so long played such a major role at the company he founded in 1975 that any transformation in his role is bound to have an effect, said Rob Enderle, principal analyst at Enderle Group in San Jose.

"Microsoft is so much Bill Gates in terms of corporate personality," Enderle said. "You will see that starting to change [because] he represented such a big footprint. 'You can't help but see some level of change. I don't think there is anyone who can replace Gates. He is larger than life."

Microsoft announced that Chief Technical Officer Ray Ozzie will immediately assume the title of chief software architect and start working with Gates on all technical architecture and product-oversight responsibilities.

Enderle noted that Ozzie was hired with the intent that he eventually would step into Gates' role as chief architect. Gates likely judged that Ozzie had performed to his satisfaction and "it was a matter of pulling the trigger and letting it happen," he said.

Enderle also pointed to recent concerns about delays for Microsoft's upcoming Windows Vista operating system, which may have prompted Gates to "think it was time to make the transition."