Worked on the Fast User-Switch Applet some more. I’m basically rewriting the whole thing to be asynchronous in it’s contact with GDM, and also to increase the ease with which one can use the backend. The whole time I’ve been asking myself “would I want to use this API in a screensaver thingie,” which is Good For The CompanyTM. Anyhow, the new backend is properly monitoring /etc/shells, /etc/passwd, and $GDMCONFIGFILE (./configure option) to handle when users get added/deleted, and polls GDM every few seconds to keep it’s display list up-to-date.
I’m also looking into handling Xnest more deeply (ideally you should be able to have the applet operate in “Xnest” mode, where it does all it’s stuff with Xnest—which should be useful for, say, making gnome-session rock), and adding some minor GUI nicenesses. When the applet is in a state where it actually does stuff, I’ll put the code in CVS. Until then, here’s a desktop shot of the little test app I made:
Update: I should note that the download available from the page linked above actually does stuff, though I’m rewriting it to make it not suck.
James Cape 
Does this directly watch the /etc files or does it use the getpwent function so it work if LDAP is in use?
Both, it watches /etc/passwd, but loads via getpwent. (Which means that LDAP users won’t get real-time updates, but regular users will.)
this sounds like it could be very useful with garnome
maybe you could see about tryng to get it included?