According to a series of Twitter posts by hacking group, Lizard Squad, Battle.Net and all of Blizzard's games were brought down overnight by a DDoS attack on the company servers. The group also claims that it has gained access to company employee emails. The attacks took place in the early evening of April 13th Pacific time with games down for several hours. As of this writing, however, servers appear to be functional again.
While no reason for the attacks was given by the hackers, some have speculated that the DDoS was initiated in retaliation either for the closure of a French private server or as a result of several ban waves in Diablo 3.
Source: IGN
