Game Center (requires iPhone 3GS or later, iPod touch second generation or later) is Apple's entry into the social gaming arena. It helps find opponents and tracks achievements and high scores. Apps must be specifically written to take advantage of these capabilities.
In the light of last week's iTunes announcements, it should come as no surprise that iOS 4.1 supports Ping and iTunes TV show rentals.
For iPhone 4 owners, the new release also provides support for HDR photography (combining multiple exposures to give a better image) and HD video uploads to YouTube and MobileMe.
Bug fixes disclosed by Apple address the iPhone 4 proximity sensor performance, iPhone 3G performance, and Nike+iPod issues. Unspecified Bluetooth improvements have also been made.
What about security fixes? Please read on.
Changes have also been made to ImageIO to protect against malicious GIF or TIFF images causing buffer overflows or other types of memory corruption leading to crashing or arbitrary code execution.
FaceTime, Apple's video calling application, has been updated to improve certificate handling issues that had the potential to allow an attacker in a privileged network position to redirect calls.
VoiceOver now announces the presence of the location services icon that appears next to an app that has requested the user's location within the last 24 hours.
The update must be installed via iTunes, and weighs in at nearly 600MB.
Apple has also updated the iPhone Configuration Utility for Mac OS X and Windows. Version 3.1 is recommended for managing devices running iOS 4.0 or later.