First of all we would like to reassure you but no we were not last night victim of a DDoS but instead victim of our own success! Regards Mt.Gox Co. Ltd Team.
If it was NOT a DDoS, then why did bitcointalk become unavailable and bitcoincharts too? Did they both get overwhelmed too? Ever think that you basically got DDoSed by a lot of "new accounts" running trading bots?