An updated version of the redsn0w jailbreak utility has been made available to resolve a prominent bug with iBooks and also includes other minor bugfixes that could cause crashing. Versioned as Redsn0w 0.9.10b4, the new release continues to be an untethered jailbreak for iOS 5.0.1 for the iPhone 4 & 3GS, iPod touch 3rd & 4th gen, and iPad 1, and does not provide support to any other devices.
Fixing the iBooks problem for already jailbroken devices is simple enough, all that is required is to download and run Redsn0w 0.9.10b4 over an existing iOS 5.0.1 jailbreak to apply the fix.
Download Redsn0w 0.9.10b4
Alternatively, the Corona untether has also been updated which applies the same iBooks patch without the need for using redsn0w again. Corona can be downloaded on any jailbroken device for free through Cydia.