I think that tddium needs guard-jasmine in order to run the rake task (see guardfile) but I will experiment with that.

I ended up going with this route because it was recommended in a Railcast on testing with Jasmine in a Rails app http://railscasts.com/episodes/261-testing-javascript-with-jasmine-revised and because I'd implemented it before and it worked well. 

I can look into jasmine-headless-webkit if we think that is a better choice, but Joe says that there is no actual Phantom/Webkit collision (or at least we've never had one reported)