First, Google refuses to let anyone remix Android with their own Linux distro, which is cheating, as far as I'm concerned. Then, their wonderful SDK can only be used to dev for Android, no other Linux platforms. Bad enough Google, one of Linux's biggest stumpers, doesn't get it.
Now, manufacturers have a problem.
Motorola makes the Droid X. A guy decided to try tinkering with it. Turns out the Droid X has a hardware locked bootloader called eFuse. When the phone starts, it passes information to eFuse which checks to make sure it matches its firmware configuation (OS, mem test, etc.) If anything doesn't match, eFuse bricks the phone. Not refuses to start, it breaks the phone. Fixing it requires a hardware fix, which can only be gotten from Motorola.
Folks, I would like to point out that Apple is a proprietary company, but they do NOT stop you from loading other OS'es on their hardware if you so choose. You got a MacBook and want to dual boot Linux and OS X? No problem. Here's a company with a Linux-specific device, that you are free to alter as you see fit, and they will bomb you for tinkering with something you legally bought and own, the software of which is COVERED BY THE GPL!!!
Hello, Moto? Good bye! And I'm glad I didn't buy one of those stupid things this weekend!