[umbramei]

For those that didn't read through the entire linked page, there is also an Eclim client for Emacs under active development (https://github.com/senny/emacs-eclim). I don't know that it's quite as feature-rich as the Vim version, and it's certainly less well-documented, but it does add some nifty IDE features to Emacs without forcing you to do your development inside Eclipse itself.