Fom Planetbeing on reddit 1 day ago:
"Somewhat contradictory. They claimed they had no way to turn off code sign on July 21:
https://twitter.com/UnthreadedJB/status/359123979979591680 But turning on verbose mode requires adding a boot argument to the kernel. Another boot argument can turn off code sign, so the ability to do one implies the other. Adding a boot argument requires a bootloader level exploit AFAIK.
Given the current evidence,
the simplest explanation is that something is being faked: i.e. either the video or the tweet is a lie."
It is a repackaged evasi0n which lifts the 5.1 restriction that the evad3rs put in place.
http://www.reddit.com/r/jailbreak/comments/1j4u02/we_hav_releese_isounthreadedjb_redy_4_dl/
Saurik also pitched in the reddit thread.