I have just started doing research, but I assume that other people might have the same question: Is it possible to read data from different sources for a FirefoxOS application, such as reading from RSS feeds from different domains?
Are you constrained by same-origin policy or is there a way to bypass it?
Yes you can! If you create a standard web app, just build a web app like you normally would outside of Firefox OS. If you create a packaged app, include a request for the network-http permission in your web app manifest. This will give you unrestricted HTTP access.
See the manifest spec for more information on permissions:
network-http - Make HTTP requests without any origin restrictions.
https://developer.mozilla.org/en-US/docs/Apps/Manifest
Edit: The permission has since been changed to systemXHR.