Massively has been following the latest content update for Lord of the Rings Online, which is Volume II Book 8: Scourge of Khazad-Dûm. We've now learned via MMeOw that Scourge of Khazad-Dûm will release on June 23 (US/Oceanic)! As a bonus, players can already download the patch; the update weighs in at a fairly hefty 600mb and links can be found in the official announcement on the LotRO forums. The patch notes are epic in length, and it might just be quicker to re-read one of Tolkien's works, but they seem to cover everything that's changing in Lord of the Rings Online.
If the 23rd and the release of Scourge of Khazad-Dûm can't come soon enough for you, have a look through the dev tour that Turbine gave us, showing a bit of the content you'll soon be playing in Volume II Book 8.