This isn’t a rumours site, and I’d hate to receive one of Apple’s famous cease-and-desist notices… but when you get a scoop this huge, you have to pass on the word.

Here it is: Steve Jobs’ Macworld keynote will include a new addition to its wildly successful Macbook line.

The news product takes its cue from the popularity of the smallest notebooks. There is a large consumer (and prosumer) segment that will happily sacrifice screen real estate, storage space and performance for extreme portability.

So, on January 9th, Apple will launch the all-new Macbook Shuffle. At 16 grams, with a battery life of seven years, it’s the most portable notebook in history, and tucks neatly behind the user’s ear.

Specifications are unclear so far, but some details include a revolutionary Bluetooth-driven visor that can slip over any pair of eyeglasses, serving as a monitor. Although conventional wisdom holds that Bluetooth is too slow for a video display, the choice of a 200×150-pixel resolution appears to have been Apple’s end-run around that problem.

The lower-sized display (or “Cinema Nano”, as the visor is likely to be called) imposes significant constraints on the Finder, specifically the inability to read filenames. But, taking a leaf from its iPod namesake, the Macbook Shuffle avoids this problem by simply launching files randomly, a feature Apple calls Serendipityâ„¢.

And the company has anticipated the objection that users are unlikely to enjoy shuffling through all of their files until they find one they want to edit in two ways. One, there is no input device (Apple’s nickname for this function is the “no-button mouse”), making editing a thing of the past; and two, the device has only 64kb of RAM and no hard drive, saving the user from the inconvenience of access to too much of their data.

Internal Apple talking points suggest the company expects some criticism of the slimmed-down feature set. A suggested response includes “Many people laughed at Steve when he announced the death of the floppy disk. Who’s laughing now?”