meteor/scripts/admin/banners.json

{ "track": "METEOR",
  "banners": [
    {
      "versions": ["0.9.0-rc13", "0.9.0-rc14"],
      "banner": {
        "text": "Meteor 0.9.0 is now out! Upgrade to it with:\n  `meteor update`\nThanks for helping test the release candidates!"
       }
    }
  ]
}