These two aren't really related, but they're two things I had to tweak to get to work.

The dialog version that the gumstix buildroot tries to use doesn't exist in any of the locations it looks in, and I couldn't find it elsewhere. I saw a version 1.0-20050306, so I changed DIALOG_VERSION in package/dialog/ to that value. Compilation was successful.

acpid complained about unsigned chars, and I only have the vaguest idea what that means. Normally that's just a warning, but the -Werror cflag was set in its makefile, so it was failing on that. I removed the flag and it compiled. This may not be the brightest thing to have done, but I don't know C (yet), so I didn't have any other options. I'll test it later when I flash my gumstix and report back here, but in the meantime.. Has anyone gotten acpi to work on the gumstix?