Official List of New Features in iOS 4 (iPhone OS 4 Software)

iOS 4 Software Update is now released! iPhone and iPod Touch users can now upgrade to iOS 4 for Free. New iOS 4 contains over 100 new features, including the following:

iOS4 New Features [Complete list]

• Multitasking support for third-party apps*
    – Multitasking user interface to quickly move between
       apps
    – Support for audio apps to play in the background
    – VoIP apps can receive and maintain calls in the
       background or when device is asleep
    – Apps can monitor location and take action while
       running in the background
    – Alerts and messages can be pushed to apps using
       push and local notifications
    – Apps can complete tasks in the background
• Folders to better organize and access apps
• Home screen Wallpaper*
• Mail improvements
    – Unified inbox to view emails from all accounts in one
       place
    – Fast inbox switching to quickly switch between
       different email accounts
    – Threaded messages to view multiple emails from the
       same conversation
    – Attachments can be opened with compatible third-
       party apps
    – Search results can now be filed or deleted
    – Option to select size of photo attachments
    – Messages in the Outbox can be edited or deleted
• Support for iBooks and iBookstore (available from the App Store)
• Photo and Camera improvements
    – 5x digital zoom when taking a photo**
    – Tap to focus during video recording**
    – Ability to sync Faces from iPhoto
    – Geo-tagged photos appear on a map in Photos
• Ability to create and edit playlists on device
• Calendar invitations can be sent and accepted wirelessly with supported CalDAV servers
• Support for MobileMe calendar sharing
• Suggestions and recent searches appear during a web search
• Searchable SMS/MMS messages**
• Spotlight search can be continued on web and Wikipedia
• Enhanced location privacy
    – New Location Services icon in the status bar
    – Indication of which apps have requested your location
       in the last 24 hours
    – Location Services can be toggled on or off for
       individual apps
• Automatic spellcheck
• Support for Bluetooth keyboards*
• iPod out to navigate music, podcasts and audiobooks through an iPod interface with compatible cars
• Support for iTunes gifting of apps
• Wireless notes syncing with IMAP-based mail accounts
• Persistent WiFi connection to receive push notifications*
• New setting for turning on/off cellular data only**
• Option to display the character count while composing new SMS/MMS**
• Visual Voicemail messages can be kept locally even if they have been deleted from the server**
• Control to lock portrait orientation*
• Audio playback controls for iPod and third-party audio apps*
• New languages, dictionaries and keyboards
• Accessibility enhancements*
• Bluetooth improvements
• Better data protection using the device passcode as an encryption key* (Requires full restore.)
• Support for third-party Mobile Device Management solutions
• Enables wireless distribution of enterprise applications
• Exchange Server 2010 compatibility
• Support for multiple Exchange ActiveSync accounts
• Support for Juniper Junos Pulse and Cisco AnyConnect SSL VPN apps (available from the App Store)
• More than 1,500 new developer APIs
• Bug fixes

Products compatible with iOS 4 software update:

• iPhone 3G
• iPhone 3GS
• iPhone 4
• iPod touch 2nd generation
• iPod touch 3rd generation (late 2009 models with 32GB or 64GB)

* Requires iPhone 3GS, iPhone 4, and iPod touch 3rd generation.
** Requires iPhone 3G, iPhone 3GS, and iPhone 4. SMS/MMS messaging and Visual Voicemail require support from your wireless carrier.

This is the official changelog of iOS 4 provided by Apple.