Sorry, Dotcom...
I haven't heard a log-in tone on a Mac for as long as I've been using them, and frankly there's not much reason to add one. Instead of a log-in tone (as Windows machines have), Macs make the startup tone to confirm that it has powered on, but that is it. Since there isn't much of an argument FOR having a useless log-in tone, it would simply be "Apple copying Windows" if it was added. Don't count on it being in later builds or versions of MacOS.
If you
really want to have a log-in tone, you could add a sound clip to your Login Items in System Preferences > Accounts > Login Items, but it wouldn't be as prompt as the Windows noise. I'm not sure how you could add a log-out sound, though.
mk2ja