Sadly (or not so sadly, from my point of view), I spent more of the weekend playing World of Warcraft rather than writing about it. So, there will be no lengthy post about slaying virtual people in the virtual compact shelving.
However, I will say that one of the primary features about WoW which would be nice in a virtual library is the ability to ask NPC's (non-player characters, or computer-run) for directions while in a city. Not only with they give you a scripted answer, but they will put a mark on your little mini-map to pinpoint the location. If it's not immediately in your location, there will be a navigational arrow, and as you get closer, you can see where it's located. Just imagine being able to ask a virtual librarian (though perhaps not an NPC, but a player character) for reference help, and then being able to have a nav arrow or pinpoint on a mini-map of the stacks. If this wasn't online, perhaps a mini-map on someone's PDA or cell phone would be feasible. Could be a big help for all those directional questions at the reference desk!