As promised by Steve Jobs during his "Let’s Rock" media event on September 9, Apple released iPhone Software Update 2.1 on Friday. Unlike previous updates that are described simply as bug fixes, this one includes a list of specific improvements including fewer dropped calls, improved battery life, and better performance when viewing or searching contacts.

The update also reduced backup time during syncs, improved email reliability, offers faster text messaging, improved 3G signal strength display accuracy, reduced crashes when large numbers of third party apps have been loaded, added the ability to repeat incoming text message alerts twice, added an option to wipe phone data after ten failed passcode attempts, and added the ability to build Genius playlists.

Update 2.1 includes several security fixes, too. It corrects problems where sandbox application restrictions were not properly enforced, maliciously crafted font data could lead to arbitrary code execution, forged DNS information could be provided to mDNSResponder, TCP connections could be spoofed, and a WebKit flaw could lead to to arbitrary code execution when visiting maliciously crafted Web sites.

iPhone Software Update 2.1 is free and available via the iTunes application.

The update will appear in iTunes as part of the application’s weekly update check when your handheld is connected to your computer. To force the update to download and install immediately, connect your iPhone or iPod touch to your computer and click Update in the iTunes Summary tab.