Microsoft's long-awaited Longhorn operating system may miss its predicted 2006 shipping date after all.

CIO Today reports the new OS could be delayed until 2007 - and while Apple may gain from this at Microsoft's expense, it's Redmond's software and hardware partners that have the most to lose.

Privately, some Windows developers have told Macworld of their frustration with Microsoft's lack of a road map for future development, which stymies some of their attempts to deliver new products to market.

Yankee Group analyst Laura DiDio told CIO: "At this point, Microsoft has to be very careful about keeping its customers informed and sticking to a roadmap. Whenever there's a delay of any kind, you have to worry about competition."

META Group analyst Steve Kleynhans reports the likely reaction from Microsoft partners should 2006 slip by without the new OS: "If there's another delay, I think the PC industry en masse would descend on Redmond like a lynch mob," he said.

"It needs to hit the streets before the end of 2006 for the holiday season, and companies already have that in their sales projections."