You can find the full source code for this website in the Seam package in the directory /examples/wiki. It is licensed under the LGPL.
No, Seam has something much more powerful: a conversation context. The Seam conversation context is propagated across redirects (even when no long-running conversation is in progress), so you can use the conversation context to store success messages and the like.
Furthermore, Seam manages a page context for each JSF page, which allows you to store objects across JSF POSTbacks without even starting a long-running conversation. This is the ideal context for short-lived AJAX operations, which often need to propagate state through several form submits.