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GitHub User: TheCompWiz
Ok... I think I found a fix for rails 3.1. The trick is to keep from using assets. You need the page to be rendered. This may seem hack-ish... I agree... but it does work. This can probably be better refined in the future.
What you need to do, is add an entry in the routes file before the "resources" for products like so:
match "/products/index.js", :controller => 'products', :action => 'index', :format => :js
@quatermain ... I ran into the same thing. Apparently, "render" is not available to assets in rails 3.1. I'm still poking around for a solution...