There’s some talk around that Microsoft’s new Windows operating system, codenamed Vienna, is scheduled for 2009.

However, if past experience is anything to go on, it might be better to call it Windows Manyana.

Microsoft originally planned for Windows Vista (Project Longhorn) to include a number of radical innovations, including a new file handling system, WinFS, and a reijigged user interface, but, in 2003, Microsoft redirected almost its software effort to locking down Windows with XP Service Pack 2.

“We put Longhorn on the back burner for awhile,” said a spokesman. “Then when we came back to it, we realized that there were incremental things that we wanted to do, and significant improvements that we wanted to make in Vista that we couldn’t deliver in one release.”

Windows Vista has now shipped about two-and-a-half years after XP SP 2, and Vista’s follow-up is expected to take about the same amount of time, according to the company. “You can think roughly two, two-and-a-half years is a reasonable time frame that our partners can depend on and can work with,” he said. “That’s a good timeframe for refresh.”

We shall see.