Paul Singh's Crystal City specifically does not refer to itself as an innovation district, but rather an entrepreneurial ecosystem. They host a 5K run every Friday night that attracts 2,500 runners and 60,000 people at $5 per head.
This begs the question, does a city and/or college have to participate in a physical spot to be an "innovation district?" They bring contributions but often move at a glacial pace which can be unbearable for the entrepreneurial community. Without those additional participants in July 2013 Crystal City had a 40% vacancy, July 2014 a 23% vacancy, and predictions are shooting for single digit by summer 2015.
Crystal City has many the other characteristics of an innovation district: mass trans via rail, connectivity, a benevolent dictator. Wait, I wasn't supposed to tweet that last adjective. Sorry Paul, it was just too funny not to.