If you ever needed to download the source artifacts for a Maven2 project, there were several options: If you use the Eclipse plugin (either the Eclipse plugin for Maven2 or the Maven Plugin for Eclipse, also called "Maven Integration for Eclipse"), you can use the option -DdownloadSources=true from the command line or enable the "Download sources" preferences option.
Both have some drawbacks. When you use the Maven Plugin in the Eclipse IDE, it will try to download the sources all the time which blocks the workflow. If you just want to do it once, you have to enable and disable the option all the time plus you have to force the plugin to start the download (with 0.12, you can add and delete a space in the POM and save it). But it will only download the sources for a single project.
If you use the command line version to download the sources, it will overwrite the .project file and modify your preferences, etc. Also not something you will want.
There are two solutions. One would be the "-Declipse.skip=true" option of the command line plugin. Unfortunately, this option doesn't work. It will prevent the plugin from doing anything, not only from writing the project files.
So if you have a master POM which includes all other projects as modules and all your projects are checked into CVS, you can run:
mvn eclipse:eclipse -DdownloadSources=true
to download all sources and then restore the modified files from CVS. I've opened a bug which contains a patch for the skip option. After applying it, -Declipse.skip=true will just skip writing the new project files but still download the source artifacts.