Redsn0w Updated to Include iBooks Fix
MuscleNerd and the iPhone Dev Team have just released a new version of redsn0w, which includes a fix for iBooks. Earlier today, the Corona jailbreak was updated to include this iBooks fix and additional launchd fixes.
As always, you can simply run the new redns0w over your current jailbreak. Just make sure to uncheck Cydia. You can install simply install Corona from Cydia.
Update #4: The b4 version of redsn0w incorporates the 5.0.1 fix for iBooks, and also for sporadic problems with launchctl. Thanks to @xvolks for merging the iBooks (sandbox) fix from @comex's github into the overall corona untether from @pod2g! As usual, you can choose to install the fix either by re-running redsn0w over your existing jailbreak (de-select Cydia if you do that), or by installing the corona package from Cydia (it's the same set of files no matter which way you choose).
You can download the new version of RedSn0w from here.