Depends what you want to do. If you can provide a different url for your mobile applications, then it is really easy to use the Rest implementation in seam, and serve the content back as xml. Dan Allen was showcasing this for mobile client (Android).
Then all you need to do is show that xml in some type of content you markup.
You can also perform some ajax push stuff on mobile using PrimeFaces, and probably more. Check out PrimeFaces. It is compatible with Seam.