Tab-completion on host-names on OS X

I don't know if this is bash or an OS X feature, but nonetheless: today I discovered that there's tab-completion that takes .ssh/config into account! I on-instinct did a tab after writing part of the hostname I wanted and (boom!) there it was, auto-completed with a colon. So to SSH to my mini I did "ssh mi" and go "scp mini:". If this is the bash-guys or the darwin guys, I don't know, I hope to find out. Nonetheless: a big thank-you!