UPDATE, 10/11/07, 12:44 p.m. p.m. EDT: There is a new post indicating that it is now safe to use the updater. So, it seems you can now install MotB, and then simply run the updater. Here is the post.

UPDATE, 4:37 p.m. EDT: It appears that there is/was a patch available via the updater today that contained the hotfix mentioned below, but then Obsidian's Rob McGinnis posted in the forums that there was an error in this updater patch that would wipe or change the CD key installed on your computer. He thus was directing people NOT to run the automatic updater after installing MotB. A revised patch is evidently coming, but it is anyone's guess where this leaves us now. So, install at your own risk.

A little tip from your friendly neighborhood DM for getting the expansion to work properly: This post contains a link to a hotfix that resolves an issue with patch 1.10 and Mask of the Betrayer. Evidently, you will see missing text in the expansion if you don't install the hotfix. If you are at patch 1.10 (which you are if you played here on Sunday), you should install the expansion first, and then the hotfix. {mos_fb_discuss:14}