Eclipse version 3.3 does not work out of the box on Sabayon Linux (Gentoo). It likes Java 1.6.
Upon installing this JDK from SUN there was a strange error message that "run-java-tool is not available". Then, I noticed that /usr/bin/java was pointing to /usr/bin/run-java-tool. I know that it was invented with some good reasons but in order to start playing quickly with Eclipse I just removed this link and put instead:
"ln -s /usr/lib/jvm/sun-jdk-1.6/bin/java /usr/bin/java", then Eclipse was happy and me too!!!