I’m running Gentoo and Ubuntu Feisty on my MacBook Pro (Core 2 Duo), and it just refused to resume after a suspend to ram. Let this be a note to anybody else going through the frustration that I was.
In /etc/default/acpi-support, I changed POST_VIDEO from true to false.
# Should we attempt to warm-boot the video hardware on resume?
POST_VIDEO=false
Works a treat now