iOS 4.1 Changelog

iOS 4.1 update is available for iPhone 4, iPhone 3GS, iPhone 3G, iPod Touch 4G, iPod Touch 3G and iPod Touch 2G.

Here's the complete changelog:

Initial release on iPod Touch (4th Generation)`
iPhone and iPod Touch only
Improved calendar colours
Bug Fixes
Proximity Sensor problems
Bluetooth connectivity
iPhone 3G performance problems under iOS 4.0[48]
Nike + iPod fixes
Fixes White Balance issue with iPhone 4 under certain lighting conditions.
Fixes FaceTime error where iPhone 3G and iPhone 3GS users could enter "facetime://" URLs in Safari .
Game Center (Only available for iPod Touch 2nd, 3rd, and 4th generation, iPhone 3GS and iPhone 4)[49] no support for iPhone 3G [50]
Updated Carrier Settings (US is AT&T 8.0)[citation needed]
Security updates to Accessibility, Facetime, ImageIO and Webkit[51]
Improved AVRCP, adds support for Next and Previous[citation needed]
Enables FaceTime call connection via email contacts (eg. for 4th gen iPod Touch users who won't have a phone number) and through favorites[52]
Check Spelling can be turned off in Settings[citation needed]
P2P App Support[citation needed]
Improved Battery life across the board[citation needed]
High Dynamic Range Imaging (HDR) (Only available for the iPhone 4)[49]
HD video upload over Wi-Fi (Only available for the iPhone 4)[48]
iTunes adds Ping, a social music network and discovery tool[49]
TV Show rentals (Only available for iTunes US Store)[49]
Can move an existing appointment from one calendar to another
Notes syncing removed from iPhone 3G due to reported performance problems[53]
Safari 6531.22.7, Webkit 532.9[citation needed]
Restores Field Test mode[54]

New Features:
· High dynamic range (HDR) photos on iPhone 4
· Support for TV show rentals on iTunes
· Ability to upload HD videos to YouTube and MobileMe over Wi-Fi on iPhone 4
· Additional support for AVRCP-supported accessories, including next & previous track control
· FaceTime calling directly from Favorites

Game Center:
· Send and receive friend requests
· Invite friends to multi-player games over the Internet
· Play multi-player games by auto-matching with other players
· View Leaderboards and Achievements
· Discover new games from friends

Bug fixes:
· iPhone 4 proximity sensor performance
· iPhone 3G performance
· Nike+iPod fixes
· Bluetooth improvements

Sources: Wikipedia, Techhail