iOS owners with a jailbroken device will be happy to know that the latest iOS 6.1.2 update is safe for them to install. iOS 6.1.2 may fix the Exchange calendar issue, but it does not close the exploit being used by the evasi0n jailbreak.
Shortly after iOS 6.1.2 was released, the evad3rs team updated their evasi0n jailbreak tool to support this latest firmware. iOS owners that updated to 6.1.2 can download the jailbreak tool from the evasi0n.com website