Apple has released an update to iBooks, its first update to the app in six months. iBooks 3.1.1 improves compatibility between the app and both iOS and iCloud.
Apple doesn't explicitly list how compatibility has been improved with iCloud, but there had been reports on Apple support forums that sometimes bookmarks and page placements were not being synced properly across devices. Apple is planning to launch iBooks for OS X this fall, which would give the company extra incentive to make sure sync works well with the app.
iBooks is a free download.