I know it seems retarded, but things like copying second life cost the company pretty little. Ten or twenty people's work for two years, thrown out and discarded. We're looking at a couple million down the drain. A lot for you or me, but not worth worrying about for them.
Sure, those things might be somewhat embarrassing, but I doubt they have a significant effect in the long term. (Except, that is, when they turn out to be a good idea and succeed.)
Also, for Apple to be a real competitor to Google, they would have to threaten Google's core money-maker, online ads, especially search ads. It's possible iAds will end up being such a competitor, and were I Google, I'd be concerned. But I'd be much more worried that for many people, "the internet" would become "facebook," and thus I wouldn't be able to show them ads.