i agree that there's something wrong with this... waaay too easy... i've been trying to get autologin working with agetty and mingetty for some time now but i can't avoid getting a password prompt. this is the "correct" way of doing it, though, and there are instructions here:
mingetty (requires you to compile + install the mingetty package):
http://easymamecab.mameworld.net/html/autologin.htm
agetty (the default that slackware uses):
http://www.linuxgazette.com/issue72/chung.html
but your hack works for me...
if you want to log into a bash shell then use the following in /etc/rc.d/rc.local:
echo "user login"
cd /home/user
su - user -c /bin/bash -l
typing exit returns you to a login prompt (because you haven't changed anything in /etc/inittab).
as soon as bash is run, it executes everything in .bashrc (if you start it like this -- if you log in at a prompt then it seems to prefer .profile), so if you want to start x then there ought to be a way of doing it in here, but it seems that PATH and some other variables aren't set as they'd normally be, so there could be some messing around involved. you'll probably get a warning that job control isn't enabled too; i don't know how to fix this. ideas? it also kills the other terminals until you log out, which may or may not be a good thing.
hth.
dan