Available free of charge by connecting your portable to iTunes, iOS 4.1 includes 'Game Center', 'high dynamic range' photos, iTunes TV show rentals and iTunes Ping.
Also new is the ability to upload HD videos to YouTube over wifi on the iPhone 4 and promised improvements to performance for the iPhone 3G.
Other fixes should see bugs ironed out with the Nike+iPod app and improvements to the Bluetooth performance.
Let us know what you think of the update: does it improve performance on your iPhone? Do you like the new features? Let us know in the comments section below.