(1) Chinese people are blown away when a Westerner speaks Chinese, and (2) Americans are blown away by anyone who speaks Chinese.
I have been taking daily Mandarin lessons for the last few months, since I'm traveling increasingly often to Beijing to teach programming classes (in English), and want to be able to communicate more easily with my students and colleagues. I'm having a super-fun time with it, and definitely feel like I'm making progress. It's slow progress, but it's something.
My friends in the US and Israel seem to think I'm some kind of mutant super genius for being able to learn Chinese. I keep trying to tell them that a billion people have managed to do it, so it can't be that hard, but they are completely surprised that it's possible.
Moreover, even when I say something short and simple (with an undoubtedly very strong American accent and mediocre tones), my Chinese friends and colleagues are blown away, impressed by my ability to learn the language.
Zuckerberg seems to be where I hope to be in about a year or two -- namely, a with good vocabulary, decent but imperfect grammar, and a terrible accent. I can live with that.
The impressive thing here is the time needed to do this. Zuckerberg is a busy guy, and taking a few hours each week to study Mandarin isn't necessarily something that you would expect him to make time for. Then again, he just got married and doesn't yet have children. Hmm, maybe I am a mutant super genius for learning Chinese while married, consulting, and with three children...
Regardless, my wife took this news as proof that I'm doing the right thing. She's convinced that there will be even more people flocking to learn Mandarin, now that Zuckerberg has shown that it's possible.