Do you have one of the above 7 Million i-devices with Jailbreak? If so, then you should definitely iOS 6.1.3 keep away. While the new iOS version is still beta, but they will ruin you a Day.
iOS 6.1.3 is still in the beta phase and will fix the error, through which one can overcome the code lock of iOS. But apparently Apple has repaired one of the five critical vulnerabilities, with which the Jailbreak evasi0n was applied. One of the developers told Forbes, that this is a problem. When one of these vulnerabilities is stuffed, then no longer works the Jailbreak. Although you could try to find a new gap, but if Apple or all also weeds out most of the other gaps, Then it's over.
The update will certainly not mean the end of Jailbreakings, but with each closed gap the task becomes more difficult. If you own a device with Jailbreak, then you should not just blindly import the next update but to wait and see, what evad3rs says.