Apple has just released iOS 6.1.2 to address some small issues. That doesn't mean that an update can't render a jailbreak useless. Fortunately planetbeing is reporting that evasi0n appears to still be working under iOS 6.1.2. Obviously, you'll still need to hold off on updating until evasi0n is updated to recognize iOS 6.1.2 as a supported firmware.
Not yet able to test all devices, but it's looking good for 6.1.2. iPad mini wi-fi and iPhone 5 are still jailbreakable.
According to planetbeing, even though the iPhone 5 and iPad mini have been confirmed to be working with evasi0n on iOS 6.1.2, more testing is still needed before the evad3rs can release an update to support the firmware. This also doesn't mean you should update to iOS 6.1.2 right now, unless you're willing to lose your jailbreak for the time being.
If you're jailbroken, we recommend waiting for evasi0n to be thoroughly tested and updated. After that, remember you must do a restore and update through iTunes and not use the over-the-air (OTA) software update feature to update to iOS 6.1.2 or you could run into issues while trying to jailbreak.