The launch of a new expansion is fraught with extended maintenance -- Warlords of Draenor being no exception. Today's maintenance, which was already a rather large window, has been extended until 1 p.m. PST.
We'll keep you posted on any developments.
Update: Blizzard's Customer Service team now states realms will be down for an additional two hours. The new ETA is 3 p.m. PST.