Software engineering interviews are busted as hell (although, to be fair, probably not substantially moreso than other industries).

What slays me with Google in particular was they did this study a while back that found that whiteboard coding was nonsense, and then they... kept doing it. Although I'm having a hard time finding it now, so maybe I'm mistaken there.

edit: here we go, although it wasn't specifically about whiteboarding http://www.nytimes.com/2013/06/20/business/in-head-hunting-b...