I am getting the exact same error messages when trying the same "echo mem > /sys/power/state".
NVRM: ACPI: unsupported event: 2
Could not suspend device 0000:01:00.0: error -1
I am running gentoo 2.6.12-r2 kernel on a Toshiba m200 laptop. I have NvAGP=0 in xorg.conf. Nvidia bug report log attached.
Did you manage to get your suspend working. Or has anyone have an idea what the problem might be?