Apple today released iOS 5.1.1, a bug-fix update that addresses a handful of disclosed issues for all iOS 5-compatible devices. From Apple’s tech note, iOS 5.1.1:
Improves reliability of using HDR option for photos taken using the Lock Screen shortcut
Addresses bugs that could prevent the third-generation iPad from switching between 2G and 3G networks
Fixes bugs that affected AirPlay video playback in some circumstances
Improves reliability for syncing Safari bookmarks and Reading List
Fixes an issue where an “Unable to purchase” alert could be displayed after successful purchase
Apple has not yet released information about the security content of the update on the Web, but the Apple Product Security mailing list reports that security fixes address a Safari vulnerability that enabled a malicious Web site to spoof the address in the location bar, multiple cross-site scripting vulnerabilities in WebKit, and a memory corruption vulnerability in WebKit.
To get iOS 5.1.1, do one of the following:
In iTunes, select the iOS device in the sidebar and click Check for Update on the Summary screen. The download in iTunes will be very large — up to 1 GB in size — so don’t use this option if you’re in a hurry or low on disk space on your Mac.
On the device itself, go to Settings > General > Software Update. The direct-to-device update is much smaller — in the 40 MB to 50 MB range, and will thus be a much faster download.