Via massively, it seems that the billing addresses, logins, and passwords of more than 20 million SOE customers were compromised, as well as the account information on about 12,ooo credit and debit cards (the latter all came from European accounts). Apart from my EQ2X account maybe getting screwed with I personally don't have a lot to lose in this, unless of course it turns out that some North American CC info was stolen. However, I feel really bad for their European customers. Having to replace a card can be a serious pain in the butt, especially if a lot of bills are tied to it. I personally am going to go into their system and reset or clear out all of my information and passwords the first chance I get.
To my mind, this isn't quite as bad as Mythic randomly charging customers hundreds of dollars. But it's still a pretty serious black eye for SOE. I'm glad that they are at least moving quickly to inform customers, as Sente pointed out. With the entire system currently locked down, it also seems unlikely that many player accounts will have had in game currency siphoned off or have been damaged in other ways when the dust settles.