How does this happen with two factor SMS verification? Did you enable your API key?
What is the whole address and transaction id just to trace and see where it went? There is no way to cancel the transaction.
[edit]
Here is the info[1] about the transaction. It seems the transaction way relayed by IP address 71.206.70.250, somewhere in Florida (Comcast customer). It also seems the address[2] only holds your balance for now. You can call Comcast and let them know.
I think this might be related to a recent Twitter account hack that happened a month or so ago, where a fake tweet was posted on the account. I had used the same email and pw on that account. Maybe they were scanning the stolen Twitter accounts against Coinbase.
> I had used the same email and pw on that account.
You used the same credentials for a social networking site as for your Bitcoin account with Coinbase? And you didn't change them once your Twitter account was hacked?
You should probably call it a relatively cheap lesson in not reusing passwords.
Transferred to: 12aW8jPeEc9iQa5ocXCDReJ6Nij4c9xHtX
Transaction: d3f6547f901b45b3c79315e78a1bbcc988e27e6b98feab321f5628e2312b5377
I think this might be related to a recent Twitter account hack that happened a month or so ago, where a fake tweet was posted on the account. I had used the same email and pw on that account. Maybe they were scanning the stolen Twitter accounts against Coinbase.