It was 0-day when they got hit. Sad thing is that they do not tell how much time has passed since the hack.
"... previously unknown zero-day vulnerability in Adobe’s ColdFusion application server. The vulnerabilities have only recently been addressed in Adobe’s APSB13-10 hotfix (CVE-2013-1387 and CVE-2013-1388) which was released less than a week ago."
To me that reads like 'it was a former zero-day exploit", as all exploits are.
seclists.org was one of the sites hit in the hack. See how they were down "over the last week". Also note that the Adobe security bulletin was release on April 9: http://www.adobe.com/support/security/bulletins/apsb13-10.ht...
So ya, these hackers found the problem (a 0-day in Coldfusion), used it against Linode. then Linode got Adobe to look into it and found the cause.