Usage

     $ export APPENGINE_SDK_HOME="$DEV_HOME/appengine-java-sdk-1.3.8"
     $ git clone git://github.com/mtkopone/sbt-scalatra-appengine-template.git
     $ cd sbt-scalatra-appengine-template
     $ sbt
     sbt> update
     sbt> dev-appserver-start
     $ open http://localhost:8080/

Once deploying to the app engine

Change src/main/webapp/WEB-INF/appengine-web.xml:application to match you app-id

IntelliJ Idea integration:

     $ sbt idea
     > "Open existing project" in Idea