Hello,
I'm finding myself to get a clean Yes or No answer for jailbreaking ios 6.1.3.
Is it possible yet for UNTETHERED?
There will never be a jailbreak for 6.1.3.
The devs believe they have sufficient exploits to enable iOS7 to be jailbroken upon release, and have no wish to waste those exploits on an OS which will eventually be replaced.
Sorry, but you will have to wait for iOS7.
None at all. I'm guessing at the WWDC, along with new hardware, but that really is just a guess.