[chriseidhof]

Yes, Apple does that sometimes, but it doesn't always have to be a bad thing, see http://www.marco.org/2011/06/06/safari-reader-and-instapaper

As for learning Obj-C: yes, it's only widely used for building iOS/Cocoa apps. There's also Cappuccino (http://cappuccino.org/), where you can reuse your knowledge for web development. Even if you use another language, your code will probably still heavily interact with the Cocoa framework and effectively lock you in too.