gdm-guest-session 0.25 (i386 binary) in ubuntu oneiric

 This package adds support for starting a guest session through gdm's
 flexiserver, which any already logged in user can launch.
 .
 It creates a temporary guest account with a temporary home directory and
 some restricted privileges (such as not being able to read any home
 directory or do any permanent change to the system).
 .
 Call just guest-session to start the session.
 .
 The tutorial http://ubuntuforums.org/showthread.php?t=1566078 shows some
 ways to customize the appearance and behavior.