Gryffin is a large scale web security scanning platform, written in Golang and by Yahoo. It is not yet another scanner. It was written to solve two specific problems with existing scanners: coverage and scale.
Better coverage translates to fewer false negatives. Inherent scale-ability translates to capability of scanning, and supporting a large elastic application infrastructure. Simply put, the ability to scan 1000 applications today to 100,000 applications tomorrow by straightforward horizontal scaling.