Eclipse is a solid tool for creating Drupal modules, but I haven't figured out anyway to use it to create releases. Eclipse comes with a CVS plug in that allows you to checkout the contributions/modules, add your new module and commit it all, no problem. But when it comes time to branch your release(as described here: http://drupal.org/node/17570), simply trying to do: "cvs tag -b DRUPAL-5 modules/mymodule" seems to be impossible. Eclipse is not willing to branch with out also tagging the version you are branching from, and the Drupal contrib release system rejects these verison tags.