Lately there’s been a lot of talk about delays of the Windows Vista release date. Even today, for example, Microsoft declared an “80% chance” of Vista being released in January of 2007 (which also means a 20% chance of it not), over three years later than the original estimated release date for what then was codename “Longhorn.” Compare this to Apple’s strategy for revealing almost no information about its latest operating system, let alone its release date, until the very last minute (for example, Tiger’s release date wasn’t announced until April 12, 2005, only seventeen days before its April 29 release). Both companies give seemingly unsatisfying information about release dates, but which one is a better business strategy? As I don’t have a great knowledge of release date business strategies, I don’t really know, but Apple’s secrecy about it’s new operating systems probably keep other new operating systems from copying its latest features. Also, I think that as a user I would like Microsoft’s strategy of releasing public betas of its operating systems instead of Apple’s policy of only giving developers copies. Still, overall I think that I would be more happy with waiting for the final release of an operating system than losing all of the excitement about it if its release just keeps getting delayed.
Unfortunately, Microsoft uses "vaporware" as a marketing tool/business weapon. The dates that MS use have little to do with reality, except to add FUD to purchases of competing products. Longhorn has been "imminent" since Mac OS X 10.1. IE 7 has been imminent since Firefox 1.0. It's always been effective for them, and they'll continue to use it.
Apple has no direct competition for it's products (usually), so the less said the better. Perhaps it comes down to the basic difference of Apple being the innovator and MS being the follower.
Let's see what shows up in Vista that first appears in the OS X 10.5 announcements from the WWDC.
Well, at WWDC '05, Jobs stated that Leopard would be released in early 2007. But you're right--there's rarely even a month given.
In regards to JoeBob's comment, I figure this is what the 20% doubt is about. August 7, Steve announces Leopard. Microsoft looks over the features and, next week, we'll see an announcement that beta testers found some problems and they're adding a few things...
:^)