As announced last week, the iPhone Dev Team has released RedSn0w 0.9.13dev1 for both Windows and Mac. However, this latest RedSn0w update is for developers only.
The latest version of RedSn0w allows you (if you are a developer) to perform a tethered jailbreak on iOS 6. This update is an upgrade to RedSn0w 0.9.12b2.
If you are not a legitimate developer, it has been advised that you stay away, as there is no Cydia install performed with this jailbreak. The only thing you will have access to is SSH or afc2, which is certainly useful, but you have to know what you are doing.
This tethered jailbreak is compatible with few devices including iPod Touch 4G, iPhone 3GS, iPhone 4 (GSM) and iPhone 4 (CDMA).
We want to remind our readers that Cydia will not be installed. Nor will this jailbreak also hacktivate your device. Thus, we advise you against using it if you rely on an unlock, etc.
Source: iDownload Blog