Audio

• Using voice chat in iOS 5 requires setting the kAudioSessionMode_VoiceChat mode on the Audio Session, or setting the AVAudioSessionModeVoiceChat mode on the AVAudioSession object.

CalDav

• FIXED: After creating a recurring event locally on the device, the device stops syncing after hitting an error on merge. Removing and re-adding the account acts as a workaround for this.

Calendar

• All MobileMe calendars were duplicated after turning calendar syncing off and back on.
• If you launch or manually refresh Calendars on an iPad, your calendars might disappear and you will have to tap “Show All Calendars” to display them again.
• NEW: Restoring from a Seed 1 backup or earlier will cause MobileMe/iCloud calendars not to sync. Subscribed calendars will show up in Calendars but none of your event calendars will appear in MobileCal. To workaround the problem please remove and re-add the account.

GameKit

• Match data for turn based matches is currently limited to 4 KB of data.

GameCenter

• If you have an existing Game Center account which has not yet gone through the first-time Game Center flow in iOS 5, you will encounter a crash when signing into a game's login alert directly. The workaround for this is to launch Game Center to complete the first-time flow.

iBooks

• iBooks 1.2.2 may fail to display some text or images in books. Please update to iBooks 1.3 in the App Store.