Update 5 (2:15 PM PST): The process that was integrating Building Stone into the AH is actually a very resource intensive process (it rebuilds all of the AH data, actually) and normally we run it while the servers are locked during our downtime window.
I thought since you could play while it was going on, that it wouldn't be an issue... but it turns out it's been creating immense amounts of lag for all of the rest of the game, sorry about that! I've killed that process so you should see a return to normalcy soonish.
I'll have to figure out a new way to get the Build Stone listings on the AH, or possibly wait until tonight to do additional downtime.
Update 4 (1:15 PM PST): Antigua and Roberts are Online and open again, thank you all for your patience! The Building Stone listings from NPCs will take a little bit, possibly up to two hours, to appear in the AH, however.
Update 3 (1 PM PST): All game servers are currently running and we're doing our final verification before opening them up, as well as adding NPC listings for Building Stone to the auction houses.
Update 2: A bit of good luck, we were able to restore the file server OS when we previously believed we would need to recreate it from scratch. I'm currently in the process of restoring the databases and verifying them for any potential corruption. Current estimate is 1-2 hours before the game servers are online again.
Update: While it appears that we have not lost any game data (and our backups were also unaffected in the event that we need to restore from them), I will be needing to rebuild one of our file servers before we can get the game online again. Currently my best estimate for that task is up to six hours. I'll provide further updates as we progress.
We're currently experiencing a hardware failure in a critical piece of our database infrastructure. All game servers are currently down as a result. I've got our network engineers working on the problem right now, and will post additional updates as I receive them.
I'm sorry for any inconvenience this is causing, and I thank you all for your patience with us while we resolve this!