Put me down for a pre-order :) If you can publish something half as interesting as the programming-heavy "Chasing the Beam" (a history of the creative programming techniques and people that stretched the Atari 2600's commercial lifespan well through the 1980s), you'll hook a lot of geeks.
I think you might need some focus though, are you only thinking about video game systems and saving old games from stagnating on dead hardware, or Apple's two processor switches and how they dragged their users with them, or why cranky mainframes run Linux? etc.
The primary focus is on game consoles, if only because it's what I know best. However, the book is platform-agnostic; the goal is that by walking through the book and working along side it, you can go from nothing to a working (for some values of working) emulator for whatever platform it is you choose. Along with this, I'm going to be building at least one emulator along side it, with full source available (marked by chapters) so that at any point in the book, you can flip over to the source and see how I tackled things there. I don't want everyone in the world building Yet Another NES Emulator (TM), as fun as they are, so I'm really trying to make it as flexible as I can.
I think you might need some focus though, are you only thinking about video game systems and saving old games from stagnating on dead hardware, or Apple's two processor switches and how they dragged their users with them, or why cranky mainframes run Linux? etc.