As usual, John Z has pretty much nailed it.
BMW Motorrad uses the term Integral
to refer to the braking system on the 2002 and up K12LT (2001 in Europe/Canada). Technically, that's neither Linked nor Integrated as they don't fall easily into either of those definitions.
These power assisted brakes are controlled by a small processor that varies the front and rear braking forces applied depending on wheel speed, lever forces applied, and other conditions. At driving speeds and normal conditions, you will get a similar response from either the front or rear lever. But at slower speeds, the front brake lever has much more effect on the front wheel and the rear brake can be applied without generating any noticeable force on the front wheel. That's what makes slow-speed u-turns possible with light
rear brake application. Add to that the ABS functions, which attempts to limit wheel lockups under heavy braking or in slick conditions, and the power assist, which multiplies the forces exerted by the brake levers onto the calipers.
Some of the older Gold Wings had one front and the rear caliper connected to the rear lever, while the front lever operated the other front caliper. That setup (and linking all calipers to both levers) can easily be accomplished by just rerouting the hydraulic plumbing. Honda's current Linked Braking System uses multi-piston calipers with some brake pistons from each wheel hooked to the front lever and the others hooked to the rear lever, but again this is just a trick of plumbing with no real intelligence or active compensation. The BMW Integral Power ABS unit is a much more sophisticated and active unit that doesn't really fit into those classifications.
So basically what BMW has done is unique in the motorcycle world, and not directly comparable to any other brake system that you may be familiar with. And yes, it just works, very well.
There's more good info in this thread
, and a detailed description of flushing and bleeding the Integral brakes in this pdf