»In which we, finally, restore sessions

A combination of the hints in this blog and this blog led to adding four user preferences in Firefox 2.0 in order to enable the Session Restore feature.
To edit the config, either hand-edit the user.js file in your profile directory; or, through the browser's about:config URL, manipulate or add the following items:

browser.startup.page 3 [1 is the default Start Page]
browser.sessionstore.enabled Type: Boolean Value: true
browser.sessionstore.interval Type: integer Value: 30000 [the Value sets the time between restores, in milliseconds]
browser.sessionstore.resume_session Type: Boolean Value: true

Easy as pie, really, but why this is not exposed through the Preferences | Tabs widget I do not know.