Krebs has posted an interesting article/interview concerning increased malware attacks against older ATMs. These attacks appear to be focused toward older NCR devices and Krebs interviews an official with NCR in the article. ATMs still running Windows XP appear to only be the tip of the iceberg with this particular threat.
http://krebsonsecurity.com/2014/10/spike-in-malware-attacks-on-aging-atms/