I was lucky to be able to attend Apple's Worldwide Developer Conference (WWDC) in San Francisco this year and I can't imagine a better year after 2007 to have been there. Seeing your primary platform recieve a massive design overhaul and then getting an entire week to soak in all the changes is something else, and the one-to-one time with Apple's engineers is invaluable. If you're an iOS or Mac developer and you haven't been to WWDC, try to get there.
If you care about iOS and OS X at all and still haven't seen the keynote, it's worth a few hours of your time. If you're an iOS developer, you need to bring yourself up to date with the new design language in iOS7, UIKit Dynamics, Multipeer Connectivity and SpriteKit (even if you aren't a game dev) first. They will change how you design your apps. The session videos are available in the WWDC app now.
A lot of apps are going to have to undergo significant change to look and feel right in iOS7. Within a day of the announcement I started planning a ground up redesign of Taxulator, inside and out. A simple freshening isn't going to cut it. It's time to rethink how the app works and how users will interact with it. Taxulator was the first app I built for the "old" iOS and I'm excited to bring it to iOS7, hopefully in time for the official release.