[General Questions and Answers] Snakeforhire:
I doubt it very much.. Been asking myself this same question many times, but even without firing up my debugger and disassembler, an obviosu answer comes to mind : on IBM-PC compatibles (and, like it or not, even your brand-new kickass rig based on the latest 1500$-worth core i7 is still considered a IBM-PC compatible, it still carries the stigmas and limitations of the good old 8086 architecture from 30 years ago), you always have a common denominator : the BIOS (or EFI for the newer machines. But it's basically the same modus operandi, or principle of operation if you will), which passes control to the 'bootstrapper' (the part which launches the bootloader. In turn, the bootloader will be tasked with finding a launchable kernel on one of the partitions of the disks it can 'see') once the POST (or power-on self-test) is completed, and hands over control to the actual bootloader (LILO or GRUB, whichever you happen to be using), which will finish the boot sequence and load the rest of the whole circus...

On mobile devices the situation is entirely different, what with different device manufacturers using different processors (even if they're mostly all based on a basic common architecture, like the ARM specification that's so dear to our Andro-devices) and whatnot, all of which probably use very different bootloaders -which for the most part are incompatible and not interchangeable. It'd be too easy, and manufacturers would sell less hardware if we could all swap parts too easily ;)

Hence the need for a specific bootloader (or more accurately 'bootstrapper', since the crucial part is when the chipset hands over control to the initramfs. The bootloader is the next step) for each device -or at least for each family of devices that are based on the same chipset (heck, even among the Samsung Galaxy family of devices, you got a truckload of different bootloaders which are not interchangeable. Try flashing the bootloader of a SGS2 on a i9003, and you'll most certainly earn a free trip to the nearest Samsung service centre)..

Those devices are just too "cutting-edge" (and the manufacturers too busy shooting at each other's feet to even think about consumers interests, let alone actually working towards satisfying the end-user) to be standardized like the PC architecture has been standardized (and looking back, even this has taken years to accomplish and countless -and endless- meetings among the representatives of the different corporations, who all had to work together to accomplish that, and all this in spite of their conflicting interests... Just see what happened with the HD-DVD and the Blu-ray standards to get an idea of the mess it can be, and how it always winds up taking the consumer hostage, caught in the crossfire)... :/

But to answer the basic question : booting an Android via GRUB *should* be doable -provided that GRUB is compiled with the specific optimizations and adresses needed by the host architecture (it'd probably be different whether your device is based on a Exynos CPU or a Qualcomm-based ARM clone, for example)- but this kinda makes the point moot, since you'd still be needing the specific libraries that the chipset needs in order to make it work, otherwise GRUB wouldn't know how to "talk to" the device in order to tell it to 'boot this kernel out of this partition, with such and such extra parameter'.. :/