Apple really does a good job of creating a buzz. They are well aware that people will start watching the Moscone Center at least a week before the show for any banner, sign, or shipping container with a Cupertino, CA address on it. This year, of course, it's the "There's something in the air" banner, which has led to a number of predictions from WiMax-enabled MacBooks to the new ultra-portable that has been unanimously coined the MacBook Air.
I'll admit, it is fun to join in on the speculation - at least in moderation. I suppose there's some element of pride to be had if you're right, as that would put your thought process on par with that of Steve Jobs' - if only for a moment. However, there is one concern with this type of marketing that Apple needs to consider: corporate customers.
The corporate customer - which Apple is aggressively seeking now that Vista has been all but recalled - needs to plan and budget their purchases. They can't always afford to wait until mid-January (or even earlier this year with the surprise MacPro update) to purchase equipment. In fact, many of them need to use their funding by the end of the year or risk losing it. Imagine if you personally bought a MacPro a couple of weeks before they were refreshed. Now multiply that by 500 or 1000 or even 2,500 and you can start to understand the level of buyer's remorse that a corporation would experience.
Apple also needs to consider that a good number of these new corporate customers who are starting to consider Macs are not the "fanboys" that have owned Macs since Hulk Hogan being on TV was something to get excited about. Their culture is vastly different and much more calculated. Think John Hodgeman's character in the Get a Mac commercials. Corporate customers need to plan upgrades, not just go to the Apple Store and buy 2,000 Macs. They are a more conservative and calculated bunch.
As Apple courts this market more and more, I think that the veil of secrecy of "one more thing" will need to be lifted, at least with the Mac desktop & laptop lines. This will enable corporate customers to more accurately plan their purchases and feel better about their investment not being refreshed just weeks after it was made. It will also give corporate customers more confidence that there is nothing coming out in the next few months that will make them wish they did wait.
Sure, I think that iPods, iPhones, AppleTV and the more consumer-based products can still be kept secret until the keynote. Most of us know that when you get anything high-tech, its days are numbered. Apple even botched this up with the iPhone price drop a few months back.
What fun would MacWorld be without some rampant yet typically completely inaccurate speculation combined with the excitement of potentially thinking like Steve!