"...I see it as a great tool for community building here."

It is going to be especially good at drawing attention/ (interaction among the community members) once @steemsports starts blogging the leader-board stats, IMO. This may be the social media equivalent of what fantasy football was however many years ago that it started. It could be a HUGE draw for people currently sitting outside of the platform.

Mainstream adoption is what Steemit needs and I can't think of a bigger draw to your average social media, cough facebook cough, user than this steemsports event. Sports are popular with the mainstream and so is the idea of making money for little time and effort.