Well, you know. Twitter has put themselves right in the middle of a national uprising in Iran and so are facilitators or perhaps enablers of conflict. I don't want to get moralistic or anything like that, but it should be expected that if you are helping one one side of a conflict that could potentially errupt into a full on civil war, that you are not immune to attack yourself.

I'm not saying this DOS or DDOS is related to the Iran issue, but I am saying that twitter has become a weapon of sorts, a communication enabler that benefits one side of a conflict more than another, so an attack like this is inevitable, even if this particular one isn't coming from the Iranian incumbents.