Ars Technica on the unified design and code view in XCode:

Apple's developer tools used to consist of two separate applications--Interface Builder for designing user interfaces, and Xcode for writing, debugging, and compiling code. With Xcode 4, Apple has essentially integrated Interface Builder into Xcode itself. Along with the integration, Apple has morphed Xcode into a single window app, using tabs to switch between design, code, and debugging views. Separate panes allow access to various source files, error logs, code templates, interface objects, and other media.

I'm an amateur programmer at best, but the idea of a unified view for code and design is beautiful and poetic.