Hey guys, I made a quick patch against gkrellm 2.3.1 to display the current gpu temp as reported by `aticonfig --odgt`. It is a hacked version of a similar command for nvidia cards.
run the patch from the base dir of the source
cat gkrellm-aticonfig.patch | patch -p0
it adds a checkbox under built-in-->sensors-->options
"Use aticonfig for ATI GPU temperatures"
after checking it, restart gkrellm and it should show up under the sensor selection config.