It's time to start getting the files for MoM in preperation for launch!
The downloadable updater means you can download the Mines of Moria files before the expansion goes live on the Turbine servers, saving you time when they come back up on November 18th. It also means you can download the patch on a computer that you don't have LOTRO installed on (i.e. your work computer), transfer the patch to a disk or device, and then run it on the computer with a LOTRO client to update it.
The downloadable updater will download the files needed to update your client to The Mines of Moria. Please note that EVEN PLAYERS WHO DO NOT PURCHASE MORIA WILL NEED TO PATCH TO THIS VERSION. There are many updates included for all players, including Book 15, UI and class changes, and so on. After you've updated your client, when the servers go live with Mines of Moria your client will apply the patch and update itself.
I'd like to thank our very own Morarae for pointing this one out (and then taunting me with it)