Would you care to elaborate what's so groundbreakingly different about Cocoa vs Swing?

The two GUI toolkits I happen to know are Swing and Cocoa, and I wouldn't say they're fundamentally different. Both are MVC, both have GUI builders (Apple IB, NetBeans Matisse), both support object instantiation (IB, JavaBeans). Maybe the only real difference is that in Swing, a menubar is always part of a window (conceptually; I know about the Apple hack that puts in its real place).

Well, no key-value coding or bindings for Swing (so far), but that's not really a killer for me.