When I say book 13, I mean the book 13 update: Doom of the last king, The new zone forochel, new mvmp class the defiler, Fishing system, and the new LFF UI. (And whatever else Turbine added)
Every Update Turbine will update the preview server 1-2 weeks before they release it on the live servers. http://forums.lotro.com/forumdisplay.php?f=137
Edit: Here is a link to last night's dev chat with some info about book 13:
http://lotro.stratics.com/php-bin/show_content.php?content=27210
Edited, Apr 15th 2008 5:31pm by Morarae