Compatible with iOS devices running Cydia, Redsn0w 0.9.6b4 has been released by the iPhone Dev Team, following their 0.9.6b3 release over the weekend. Devices must be tethered to a Mac or PC for the process to work. [iPhoneDevTeam via RedmondPie]
We don’t have confirmation on this beyond the word of a Czech-based developer who has tested it, but apparently Apple is blocking push notification services in unofficially unlocked iPhones. However, we have tested it and it works.