Sony have released a statement revealing they have been hacked again, with 93,000 accounts globally being accessed. Sony have temporarily locked these accounts and only a "small fraction" of these 93,000 accounts showed additional activity prior to being locked. Sony are currently reviewing the accounts for unauthorised accessed and will provide more updates as they have them. Sony have also used some number play to seemingly down play the event by saying "less than one tenth of one percent (0.1%) of their PSN, SEN and SOE audience may have been affected".
Sony have used this as an opportunity to remind people of the importance of a strong password and having a username/password combination that is not associated with other online services or sites. They suggest you use a hard-to-guess password and always look out for unusual activity in your account. I've provided the full press release below: