From Apple’s knowledge base article on the patch:
Available for: iPhone 4 and later, iPod touch (5th generation), iPad 2 and later
Impact: An attacker with a privileged network position may capture or modify data in sessions protected by SSL/TLS
Description: Secure Transport failed to validate the authenticity of the connection. This issue was addressed by restoring missing validation steps.
Bottom line, this is a security patch for an SSL verification bug. You’ll find it via:
Settings > General > Software Update
Apparently, the bug has been around quite a while. Two other patches were released yesterday, this one for the Apple TV, and this one for the iPhone 3GS and iPod touch (4th generation). Seems like there’s no patch for the original iPad. Wonder if that iPhone 3GS patch includes the original iPad and they just left it off the list.
Go get patched!