If your beta character reached level 30, Blizzard's new preview offers a look further ahead. These notes leave out the individual quest stories. The linked video contains more reveals.
The beta's 1 October update set the cap at 30.
Where the questing fits
The video confirms Riverglades content for both Horde and Alliance at 2:17. Blizzard's earlier panel recap places much of its questing in the mid-30s to mid-40s.
Hyjal comes later. Blizzard describes it as the climax of leveling, and the Hyjal section at 4:42 includes Cenarion Circle questing. The separate raid mention at 5:46 is Barrow Deeps, a ten-player raid. The panel recap describes Barrow Deeps as a planned maximum-level challenge.
A small plan for playing with friends
If your friends have uneven playtime, decide whether discovering the new quests together matters. Agree on when to meet up before someone races ahead. Planning a ten-player Barrow Deeps run can be a separate conversation.
The video does not establish quest prerequisites, efficient routes or completion times. Save it for later if you would rather discover the individual quest stories in-game.