A new Bosstiary is up and reveals a lot of info behind the bosses. To me it doesn't give a lot of "new" info or anything more than the maps/boss locations, but it's still pretty cool.

They say that knowledge can be a greater boon than even the most powerful spells, or armor, or weapons. The battles that lie ahead beyond the gates of Icecrown will test your mettle like none before, and you will need all the help you can get. So arm yourself with knowledge, and discover the truth about the dangers that await you within the Frozen Halls in our new Icecrown Dungeon Bosstiary.

The Bosstiary awaits over at the official site.