radio-button-component.coffee

# {{ radio-button name='dish' value='spam' groupValue=selectedDish }} Spam
# {{ radio-button name='dish' value='eggs' groupValue=selectedDish }} Eggs
#
App.RadioButtonComponent = Em.Component.extend
  tagName: 'input'
  type: 'radio'
  attributeBindings: [ 'checked', 'name', 'type', 'value' ]

  checked: Em.computed 'value', 'groupValue', ->
    return @get('value') == @get('groupValue')

  change: ->
    @set('groupValue', @get('value'))

templates-application.hbs

{{ radio-button name='thing' value='one' groupValue=selection }} One
{{ radio-button name='thing' value='two' groupValue=selection }} Two
Currently selected: {{ selection }}

Beautiful. Sadly, it sounds like it needs an oberserver? https://gist.github.com/vasilakisfil/d055d9d2d9b56f684b42#gistcomment-1769844