I believe the environment file, 20eclipse, should specify the PATH variable to the binary eclipse PATH=/opt/eclipse
This is an issue with the eclipse-sdk-bin that does affect eclipse-sdk. I'd ask you to upgrade to eclipse-sdk and help us stabilise it. If you still prefer to run eclipse-sdk-bin, repoen this bug, and I'll add a symlink /usr/bin, called eclipse-2-bin (to avoid conflict with the coming /usr/bin/eclipse-2 and /usr/bin/eclipse-3 symlinks).