Conversation scope and browser tabs

[gonorrhea]

from WB ref doc: 

the conversation scope holds state associated with a particular web browser tab in a JSF application.

I know that, for example with IE 7, that Seam starts a new session when user starts a new browser instance/process and new conversation for new tab or new window.

How does Web Beans RI (or Seam for that matter) know that a new tab has been selected/started?  Is it based on the lack of conversation-id for the new tab's HTTP request?

[nickarls]

Surely, a new HTTP session is not started?

If no conversation id is propagated, a new, transient conversation is started (no matter if the URL is processed in another window or another tab)