There have been issues with iBooks DRM and the recent RedSn0w update fixed this problem, this was all to do about a few images not displaying properly, and in some cases not showing up at all. Well you will be happy to know the Corona untether has had an update also that fixes this.

There is also more news via Saurik; Corona 1.0-8 has also been updated to support iPhone 4S on iOS 5.0 as well as the iBooks DRM fix. Corona version 1.0-7 is good for those with jailbroken devices running iOS 5.0.1, but not for iPhone 3GS old bootrom.

All users need to do is open up Cydia and install the new version; according to iDB they suggest running RedSn0w is you have not installed Corona yet.

So there you have it, if you are having problems with iBooks on jailbroken devices just run Corona via Cydia, please do let us know how you get on? Anything you can provide us gives us a better knowledge about these updates.