While attempting to migrate ember apps to ember-cli rather than grunt-cli, HTMLBars rather than handlebars and history API rather than hashchange, my new test projects got a 'undefined is not a function' due to the rimraf module now requiring glob and some problem in using that.
I still had a working project where ember-cli node_modules have the older rimraf so I replaced the CLI node_modules with the older ones and was able to get test projects running again. I'm still using ember-cli 0.2.0-beta.1 because 0.2.0 caused me other issues.