Apple announced this afternoon the release of iPhone OS 3.0.1, Available for: iPhone OS 1.0 through iPhone OS 3.0

As quoted from their website

Description: 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 Fraunhofer SIT for reporting this issue.

Meaning that an update on our post from yesterday was dead on (kudos to the BBC and Computer World), this patch should be available via iTunes.