Application Frameworks: "Designing Apps with Scroll Views" (awesome thought process of engineering UI code)

iPad and iPhone User Interface Design (excellent design principles and examples)

Advanced Performance Optimization on iPhone OS, Part 1&2 (tips and tricks galore)

Using the Camera with AV Foundation (What FaceTime is built on)

Can't find it yet - but: Building dynamic server-driven user interfaces

> Can't find it yet - but: Building dynamic server-driven user interfaces

There are slides for Session 117 - Building a Server-driven User Experience under Application Frameworks, but no video posted.

The multitasking ones were very helpful.

If you're wondering what Xcode 4 will be like, skim through the Developer Tools State of the Union slides.