It comes from Chinese crack squad Team Pangu, and will let users root their smartphones in order to eschew Apple's software limitations.
It arrives faster than the first iOS 7 jailbreak did, but as of right now the latest hack doesn't come with Cydia, a popular tool for installing software unavailable on the App Store.
We wouldn't advise doing it, of course. It'll void your warranty for one thing, and there's also the risk of bricking the phone.
Via Redmond Pie