Back on track.
Night elves and draenei both get dumped out of their starting experience in the Northern part of Darkshore, via a boat from each of their capital cities. Before Cataclysm, they'd come down the dock from the boat and immediately find themselves in the main quest hub of the zone, Auberdine.
However, as shown in the cinematic introduction for Cataclysm, Deathwing did a flyby and completely torched the place.
Now, the old quest hub is in ruins, and the survivors have relocated further north. Where the old version of the zone had you dealing with encroaching naga (villainous fish people) and furbolgs (bear-like creatures), now there are trolls feeling encouraged by the elves' setback who are making their way up the coast. It's your job to rescue survivors, find supplies, and fight off the trolls, among other things.