Apple has released iPhone OS 3.0.1 to handle the venerability issue of iPhone SMS messaging system. This is recommended to all users of iPhone OS 3.0, that they must upgrade with OS 3.0.1 as soon as possible directly from Apple iTunes.
This new OS is just supporting iPhone users who have contracts with carrier service providers not for jailbroken iPhones. So, jailbreak iPhone users be warned that do not get upgrade to iPhone OS 3.0.1 because it may take your iPhone out of order.
So, jailbreak iPhone owners, be patient and wait for any solution by iPhone Dev Team and until then don’t open any received text message from any one even by known people this is a precautionary advice to save the devices by hackers attacks.