EiffelStudio is the new Eiffel compiler by Interactive Software Engineering. It includes not only a command line compiler, but also a powerful IDE with several unique features, such as an integrated reverse engineering tool and a quantitative code analyzer.
To get started, follow the provided guided tour.
To see the new features and improvements over previous versions of the ISE Eiffel environment, have a look at the What's new section.
An quick overview of the new graphical interface is available here.