grails create-app doesnt generate the eclipse preferences at the moment. Since the grails preferences are different than the defaults they have to be changed after every create-app ("Disable Groovy Compiler Generating Class Files" has to be checked). This is described at http://docs.codehaus.org/display/GRAILS/Eclipse+IDE+Integration but it's of course better to avoid this, even more because this is something many new grails users will encounter and be puzzled by (at least I was )

Patch is included