Session saving was removed during the development of Natty, so presumably, it's not in Oneiric either.
Here is a notice on what we decided during the Rally: we drop session
saving from natty in Ubuntu. The disablement is already effective in
== Why removing it? ==
We saw a lot of side effects during the previous cycles when we
started to use multiples session (like in UNE, desktop session and
- the saved applications contains the list of all running application, including the window manager, the panel and suchâ€¦ Consequently, we
got a lot of patches and hack to avoid saving mutter, compiz,
metacity, and the panels in lucid and maverick, so that when someone
wanted to start a session, the required components from the session
will indeed been launched instead of the saved one.
- We tried last week to change the desktop order but it went quite wrong with a lot of settings and we had to revert it.
- In addition to that, session saving never really worked with all the default applications we have (for instance, openoffice, firefoxâ€¦)
and even with supported applications like gedit: the opened documents
weren't started again, making the feature quite useless.
The information above was derived from this source (visit this link for the full details): http://www.linux-archive.org/ubuntu-desktop/478109-gnome-session-saving-dropped-natty.html
Maybe you could suspend your computer instead of logging out? I believe that "saves" your session as well, as everything is there when you bring your computer back from being suspended.