The new iOs 6 will be released tomorrow and many people will do the update. If you currently have a jailbroken iDevice and you want to keep your jailbreak, do not update! If you upgrade to iOs 6 you wouldn’t have your tweaks and jailbreak anymore.
There is a jailbreak tethered for the iOs 6, but it doesn’t install Cydia. There is only few packages that are compatibles with this new iOs version.
So save your SHSH, be careful when you open iTunes and all will be ok :).