I recently saw a blog post by Marek Palatinus that a Linode administrator user has been hacked and that their internal customer support interface was used by the hacker to access customer accounts.
We were alerted to the suspicious activity and have identified and corrected the issue. Our investigation has revealed a customer support interface was used to access your account. The compromised credentials have been restricted and we are discussing policy changes to prevent this from recurring.
According to this forum there are also other accounts on Linode targeted which had BitCoin wallets worth several thousands of dollars stolen.
If these reports are correct it would probably mean that they had unlimited access to most of Linodes customers data.
Update: Linode has confirmed the breach and said that 8 accounts that were dealing with bitcoins were specifically targeted.