I missed that old sound, but a recent post on OMG Ubuntu showed me that it is still present in a default install and all it needs is a new entry in Startup Applications to activate. You can specify any application that plays sounds to open it up in, but if you don't want that application sitting there after the sound is played, then install and use the command line version of VLC instead. You can get it by invoking:
sudo apt-get install cvlc
Once you have it, make a new entry in Startup Applications using the command:
cvlc /usr/share/sounds/ubuntu/stereo/desktop-login.ogg
Try it! The only negative to this approach is that the sound doesn't play until after the desktop is fully loaded.