There’s a new Cocoa programming blog out. It’s supposedly by an Apple AppKit and Foundation developer. Anyway, he has a nice article that explains in detail why a message to nil will only return nil for objects and a few same-size integral types.
If you haven’t read this info on Cocoa-Dev yet, or if you’re curious about the runtime architecture necessities that actually cause this (documented) discrepancy, you’ll want to read this article.
If you don’t want to, then just see this as a life sign from an Uli with a cold and two out of six performances to go before regular programming life can resume.