This year’s Mac Expo teaser banner uses a lighter Myriad font than the company has used in recent years.

An early peek at the Moscone Center in San Francisco, site of the upcoming Mac Expo and, more importantly, Steve Jobs’ foremost keynote presentation of the new year, reveals a new slogan for 2008: “There’s something in the air.”

Those of us who dissect every clue and rumor leading up to the big day will immediately notice something askew with the trademark black banner: It seems Apple has a new font in its arsenal.

Whether this represents the beginning of a product-wide shift or an expo-only appearance remains to be seen, but it is certainly a conscious move away from its traditional font, Apple Myriad. Conceived as “a modification” of Adobe’s Myriad font family, Apple Myriad was “produced by Galápagos Design Group,” as noted by Wikipedia, and “incorporates minor spacing and weight differences from the standard varieties.” Apple began using this clean, semi-bold font across its product line around the time the iPod landed, and it has since become as recognizable as the partly eaten fruit it flanks.

Apple’s Think Different campaign featured the Apple Garmond font, like on this Muhammad Ali ad.

Before the unique Myriad font, Apple was partial to serifs, a simple, stylish font popularized by the ubiquitous “Think Different” campaign. Dubbed Apple Garamond, it was first used in the original Mac ad and can be found on nearly two decades of products and marketing materials, from PowerBooks to posters and everything in between.

The infamous 1981 ad where Apple welcomed IBM into the computer market with open arms used the company’s original logo, adorned with the Motter Tektura font. Interestingly, the font for the ad copy is closer to Apple Garamond, which wouldn’t make an official appearance until 1984.

And prior to Garamond’s appearance, Apple font of choice for its logo was Motter Tektura, a futuristic, space-aged series of letters with slants and curves that was just slightly ahead of its time. It didn’t last too long, but Motter Tektura set Apple apart from its contemporaries and established its rebel mindset from the get-go.

In short, Apple chooses its fonts carefully and a change – even one as simple as skinnier letters – is no small matter. And coming on the eve of a Mac Expo, it’s sure to get people talking.

And to think, we haven’t even heard a single word from Steve yet.