The following kind message can be found in the Battle Net Realm Status Pages:
"We have recently become aware of the fact that an individual,
group or entity has instituted a server attack on both Battle.net
and Blizzard's web pages. The result of this illegal activity has
been that many of our customers are having difficulty logging on
to the Battle.net game service and accessing Blizzard web pages.
We are in the midst of implementing a solution, but we wanted to
let you know that the situation is a direct result of attacks on
our servers, not Battle.net stability.
The FBI and certain European law enforcement agencies have been
notified, and we are working in conjunction with them to identify
the individual. Attacks on our servers will not be tolerated, and
Blizzard fully intends to prosecute this individual to the
fullest extent of the law.
If you have any information about the individual, group or entity
involved in this activity, please email hacks@blizzard.com.
Thank you for your patience. We will post updates on the status
of the servers as more information is available."