Looking at the scientific papers, you can see that humanity is getting ever-closer to true bionic people. Fully-functioning robotic arms and legs are becoming more common and more lifelike all the time. Though we're not quite to the phase where people are doing this sort of stuff voluntarily. However, by the year 40,000, that has changed. Forge World has started taking orders for their new The Horus Heresy - Mechanicum: Taghmata Army List book as well as a new Mechanicum Magos Macrotek Enginseer and Servo-Automata. They've also got a new Knight Scion pilot.
The Taghmata Army List book compiles the various rules for Mechanicum units from the Horus Heresy Books 1 and 5 into one place, making it easier to run armies so you don't have to carry around several books to do so. But it's not just a re-hash of older books. There's new units included, too. Also, there's updated rules for playing Warhammer 40k in the Horus Heresy era.