It doesn't appear to be working on Dapper, at least for me. Here's what I get:

mike@Home:~$ sudo gcc-3.4 -o autologin autologin.c
/usr/bin/ld: crt1.o: No such file: No such file or directory
collect2: ld returned 1 exit status

And I also tried this:

mike@Home:~$ sudo gcc-4.0 -o autologin autologin.c
autologin.c: In function ‘main’:
autologin.c:2: warning: incompatible implicit declaration of built-in function ‘execlp’
/usr/bin/ld: crt1.o: No such file: No such file or directory
collect2: ld returned 1 exit status

Any ideas??