> As far as I know, main is ALWAYS required to return int in ANSI C. Has this 
> changed with the latest drafts of the ISO and/or ANSI standards?

Not in a "freestanding" environment, like this case. A bootloader is not
just another program run from the shell. The kernel itself is another
example.

ANSI/ISO makes no promises on the signature of main in such environments.

Martin