The Dev Team has just updated Redsn0w to 0.9.9b7 for both Mac and Windows. This update reduces the time it takes to jailbreak your device on iOS 5, it cuts the time down from 210 seconds to 80 seconds, meaning it is 60% faster.
Here is a further explanation of this update via the Dev Team:
After some feedback on reddit, we’ve decided to make the initial jailbreak as quick as possible by no longer “stashing” the applications by default during the redsn0w run. This reduces the time to actually perform the jailbreak from 210 seconds to 80 seconds (60 percent!). However, you make up for much of that the first time you launch Cydia, which will then want to stash the applications. You can choose whether you want redsn0w or Cydia to stash in the Preferences pane.
A screenshot of the new version can be seen below. You can also download the new version on the downloads page.
