GreenPois0n jailbreak update RC6.1 fixes iBooks blockade
After a bit of trouble with iBooks checking for the ability to run unsigned code, and then refusing to let you read books you'd paid for, the Chronic Dev-Team have updated GreenPois0n to RC6.1. They've matched the iPhone Dev-Team's PwnageTool and rolled in Comex's iBooks fix, which blocks the check, meaning that you shouldn't have any issues going forwards.
While there are less and less reasons to jailbreak these days, there are still a few key apps, customizations and utilities that you simply can't get any other way. So if you're a fan of SBSettings or want custom SMS tones, then head on over to the GreenPois0n site and download RC6.1 for Windows or Mac.