I'm going to be the contrarian voice and disagree with all of this. This type of interview process is seriously inefficient. All of the "soft technical" skills you're measuring with this process can either be judged by a single conversation, or can easily be learned. The only thing about software development that can't easily be learned or enforced is problem solving ability. This is where puzzler type interview questions come into play.

Comp sci "puzzles" are a microcosm of the types of mental processes needed in day-to-day development. Having the developer code on the whiteboard tests communication skills, ability to analyze and handle critiques, etc in one shot, while also testing the most critical skill that can't be learned or enforced later on.

All these "hacking interview" ideas are missing the problem. For top companies, the only problem with the interview process are finding enough good people and the potential false negatives. The process described here just turns the problem of false negatives into the problem of false positives for these companies. This really is no solution.