Using open source code is not ripping it off.
When you leave a bag of chocolates open and invite your friends to have their fill, you lose the right to say that they stole from you when they go ahead and grab those chocolates.
Open source is supposed to be all about selfless sharing, isn't it? You can only be selfless when you don't expect anything in return.
I'm pretty sure Microsoft uses open source code in their products too. The only difference is that Apple proudly admits they do so, contributes something back to the community (I'm not sure how much it is but it has got to count for something) and their CEO does not go yelling around that they are going to sue Linux vendors for unproven patent violations.
Of course, every company is in the business to make money and you cannot expect anyone to be saintly. Least of all, Apple Inc.
