A flaw that could open up every iPhone in the world to attack was made public by a pair of hackers earlier this week. Now Apple has moved to patch the hole in the iPhone's security.
Security update 3.0.1 has been rolled out to fix the SMS security vulnerability. It's available now for all iPhone models and OS versions. Apple is advising everyone who own as iPhone to update their devices. Of course, as with every official update, this could adversely affect homebrew apps.
Here's a description from the Apple Support page:
A memory corruption issue exists in the decoding of SMS messages. Receiving a maliciously crafted SMS message may lead to an unexpected service interruption or arbitrary code execution. This update addresses the issue through improved error handling. Credit to Charlie Miller of Independent Security Evaluators, and Collin Mulliner of Technical University Berlin for reporting this issue.