From an Engadget update, here is Apple rep Tom Neumayr had to say:
We appreciate the information provided to us about SMS vulnerabilities which affect several mobile phone platforms. This morning, less than 24 hours after a demonstration of this exploit, we’ve issued a free software update that eliminates the vulnerability from the iPhone. Contrary to what’s been reported, no one has been able to take control of the iPhone to gain access to personal information using this exploit.
Apple has also posted a security document describing the issue. You can check out the read link below for the security document.
Read Apple Security Document