All the tech nerd/mac nerd sites keep pointing to the UDID ban as the big news of the day. While that is indeed important, and every developer should make sure none of their code or 3rd party dependencies like crash reporters or ad networks use the UDID anymore, I think the most overlooked item of the day is Apple's second post.
As of May 1, iPhone 5 support is required. While this may be great news for those iPhone 5 users who are tired of apps not using those extra 88 points of vertical realestate, it is the final nail in the coffin for those still using iOS < 4.3 and iPhone 3G or iPod touch 1G/2G devices.
While most app developers had already set the minimum version supported of their products to 4, 5, or even 6, it was still techinically possible to support all the way back to 3.2 by using Xcode 4.4. That's because Xcode 4.4 still allowed you to target iOS 3.2 and create armv6 binaries. With Xcode 4.5, apple stripped armv6 support and set the minimum iOS target at 4.3. Apple has also decreed that if you want to support the iPhone 5, you must build with the iOS 6 SDK and at least Xcode 4.5, even though it still technically works with the iOS 5 SDK on Xcode 4.4 (Apple ties SDK versions to Xcode releases).
Yes, I know if you google hard enough there are ways to partially build in Xcode 4.5, take those results and re-build and archive them on Xcode 4.4 and submit THAT franken-binary, but that's way outside supported territory getting into submission rejection land for doing funky things. Bye Bye iOS 3 and iPhone 3G owners. It was nice knowing you, but at least now everyone can transition to ARC without feeling like it was their decision to cut off older customers.