As of Solaris 9, Sun introduced a new utility called Service Management Facility. This utility is now (Solaris 11) the preferred method of managing your services. While the /etc/rc.X/ directories are still around and work they are considered legacy.

Here is a quick example of enabling apache to get you started.

# svcs -a | grep http  
disabled 10:23:11 svc:/network/http:apache22  
# svcadm enable http  
# svcs -a | grep http  
online 10:30:23 svc:/network/http:apache22

This will enable apache for not only your live session but will also enable it for boot as well.