The Eclipse Common Build Infrastructure aligns the build setup of Eclipse projects and make building an Eclipse based project trivial for external people.
Take building the Eclipse platform for example. Given that you have Maven, Git and Java installed you get a shell and issue the following commands:
git clone -b R4_2_maintenance --recurse-submodules \ git://git.eclipse.org/gitroot/platform/eclipse.platform.releng.aggregator.git LOCAL_REPO=$(pwd)/localRepo cd eclipse.platform.releng.aggregator mvn -f eclipse-parent/pom.xml clean install -Dmaven.repo.local=$LOCAL_REPO mvn -f maven-cbi-plugin/pom.xml clean install -Dmaven.repo.local=$LOCAL_REPO mvn clean install -Pno-bree-libs -Dmaven.test.skip=true -Dmaven.repo.local=$LOCAL_REPO
and after a few hours you have your own custom build of the Eclipse IDE.
Basically all the cool Eclipse projects, like EGit, Mylyn, Platform have already migrated. You find the complete list of migrated projects here: Eclipse projects using CBI.
I think it would be great if more projects migrate, as this would help others to created custom flavored builds of Eclipse.
Also we are planning a little “build your own Eclipse IDE” context on EclipseCon 2013, so running the build or migrating a project would be a great practice.