We (Jon McCann and myself, with some input from others) have been working on a design for a new user management tool, with the goal of coming up with something better than the current trias of system-config-users, gnome-about-me and gdmsetup.
The design is not finalized, you can see the current state of affairs here: http://people.redhat.com/mclasen/user-account3.pdf.bz2 (I really wanted to put this on the wiki, but all I could only get proxy errors when trying to do so).
Comments are welcome. Please note the section on target audience and use cases.
Matthias