Mixpanel was a cool interview. I remember the question was about data structure for a rank system (it was a heap). The office in SF is beautiful, and the lunchtime catered food, was great.
I guess I'd have more to say about MA if I knew more about it! I did not try it yet and I don't know how they make Chrome faster in the cloud and deliver a seamless broadcast of the screen to the user, but with enough smart people, I'm sure it's possible.
As I said in a previous comment, I definitely think the future is mreo 'app virtualization' in the cloud, in some sense perhaps MA is starting at the beginning of that curve.