The reports of ‘ransom’ locking of iDevices from Australia are starting to spread to other countries, including the US. The process involves locking your phone as if you had reported it stolen. The attacker changes the access PIN on your phone, and asks for $100 (US/Euro) to unlock.
One clear explanation is here http://www.symantec.com/connect/blogs/apple-ids-compromised-iphones-ipads-and-macs-locked-held-ransom .
Any iDevice user (not just iPhone) should immediately change the password on their Apple account, and also change the access lock code on their device. The above article has good advice on what to do to prevent the attack.