What's so special about Seam's sta...

Can Seam handle back-button naviga...

Yes. Seam supports fine-grained user state management beyond the simple HTTP session. It isolates and manages user state associated with individual browser window or tab (in contrast, HTTP session is shared across all windows of the same browser). So, in a Seam application, each browser window / tab can become a separate workspace that has independent history and context. Multiple user conversations can be supported for the same browser. This behavior is similar to that in rich client applications. To see this feature in action, just run the booking example application and try to book several hotels via several browser tabs in parallel -- you can see that each tabs retains its own progress in the booking conversation.