I think Rob Pike half-heartedly mentions in a couple of the twilight videos introducing Go that Ken and he got together to conceptualize go after he walked into

I think Rob Pike half-heartedly mentions in a couple of the twilight videos introducing Go that Ken and he got together to conceptualize go after he walked into the office one day and got tired of a google server binary taking ~40 minutes to compile. Not sure if it this is the real reason, but it's a great story.