if you want to run "hosted" mode, where the javascript and java is executed by eclipse, then yes, GWT requires eclipse.

GWT itself does not have a "desktop" mode, it does not have a "desktop" version, and so GWT apps cannot themselves be run as a "desktop" app unless you use the GWT Eclipse-basesd "hosted" mode - or you run the GWT-compiled javascript under Adobe AIR, Mozilla's Gecko / Spidermonkey, etc. etc. etc.