With the unexpected release of the evasi0n7 jailbreak, we are finally able to release the 3GS/A4 6.1.3 + 6.1.5 untether Cydia package.
To grab it...
1) Have a tethered jailbreak (either via redsn0w [Point to 6.0 IPSW] or sn0wbreeze).
2) Open Cydia.
3) Click the "Changes" tab in the footer.
4) Press the "Refresh" button in the top left corner.
5) After "Reloading Data", perform a search for "p0sixspwn" (the O is a zero).
6) Tap Install.
That's it! You're untethered.
I'll be updating sn0wbreeze to incorporate the untether directly later (No eta :P).
Our next priority is getting an A5+ jailbreak for 6.1.3/6.1.4 out. As I stated on Twitter, we expect it should be out by Christmas day. So if you don't feel like upgrading to iOS 7 and prefer 6.1.3/6.1.4, sit tight for a bit. :)
A guaranteed drama-free untether (hopefully :]).
If you have intentions of submitting us donations, submit 'em to the EFF directly.
@p0sixninja (for the name ;P)
@saurik (for hosting :))
If you have an questions or issues, please direct them to the JailbreakQA forum where *awesome* people will help you! :)