there is a usability list gnome usability discussion, but I'm not sure if it falls there. Novell has a usability team that does usability testing with different profile of users and derives results out them. http://www.betterdesktop.org
That's really an amazing work they put into this! In regards of using tabs, I found these 3 Flash animations of Lotus Notes 8. ftp://ftp.software.ibm.com/software/lotus/lotusweb/ln8_demo/ln8_demo/access.swf ftp://ftp.software.ibm.com/software/lotus/lotusweb/ln8_demo/ln8_demo/contacts.swf ftp://ftp.software.ibm.com/software/lotus/lotusweb/ln8_demo/ln8_demo/email.swf They are from this link: ftp://ftp.software.ibm.com/software/lotus/lotusweb/ln8_demo/ln8_demo/