When you login you could just open the Terminal and type: last
This will show you all the users that have logged in, when they logged in, for how long they were logged in and whether they logged into the terminal or just regular login. My list goes all the way back to the beginning of the month.
I know it's still not what you want, but I don't know if there's a way to get that functionality back in Jaguar.
**edit** If you enable the "Other" user in the list option supposedly if you go into NetInfo Manager and delete the Long User Name (or actual name I think?) for a user, they won't show up in the list but you can still login as them by clicking "Other" and typing the username and password in the text fields that appear. Still, I think at this point the only way you're going to be able to tell who logged in before you in Jag is to use last in the Terminal.