There is a bug out there for the iPhone that infects through SMS. It can then spread through the contacts list and apparently there is only one way to stop it. This has the potential to be ugly.
"Earlier today, Apple finally released iOS 5.0.1. The update includes a fix for battery life issues that some iPhone 4S users are experiencing, Siri improvements for Australian users, multitasking gestures for the first generation iPad, and an important fix for the Smart Cover security flaw that was revealed last month."