It's not just multitasking apps that are hitting the App Store to coincide with the release of iOS 4.0 -- Apple has also just rolled out version 1.1 of its iBooks app, which is now available for the iPhone and iPod touch in addition to the iPad (officially, this time). As previously announced, the app now also supports PDF viewing, and boasts a range of other more minor improvements, including new ways to bookmark (complete with syncing across devices), yo