iTunes

• The version of iTunes that comes with beta 4 cannot sync devices that have the beta 2 software installed. To avoid this problem, do the following:
  1. Sync any devices that have beta 3 installed to the version of iTunes that came with beta 4.
  2. Upgrade iTunes to the version that comes with beta 4.
  3. Connect the device and install the beta 4 software. (Understand that you might see a failure to sync error when you first connect the device.)
  4. After installing the beta 4 software, restore from your the backup you made in step 1.
• Videos purchased from the iTunes Store do not play on a 2nd generation AppleTV over AirPlay with iTunes 10.5.

Location

• NEW:The startMonitoringSignificantLocationChanges method of CLLocationManager does not cause applications to be resumed or launched in the background for significant location change updates. However, if a backup from a previous software version (where an application was monitoring significant location changes) is restored to the device, significant location change monitoring will continue to cause that application to be resumed or launched in the background.

Mail

• NEW:Forwarding a message with attachments included does not attach the file and the message compose screen does not change from “Loading….”

Music Library

• NEW:Some songs are missing their album artwork after changing the device library via syncing.

OpenGL

• NEW: In iOS 5.0 beta 4, several OpenGL extensions have been moved from the APPLE namespace to the EXT namespace, causing some API to be renamed. The altered extensions are EXT_color_buffer_half_float,EXT_occlusion_query_boolean, EXT_separate_shader_objects, EXT_shadow_samplers, EXT_texture_rg, EXT_debug_label, and EXT_debug_marker.

OTA Software Update

• NEW: If you are doing a OTA software update from beta 3 to beta 4, you will need to re-sync your photos with iTunes.”