...at the Value Investing Congress in NYC.
His slide deck is titled, "Field of Schemes: If You Build it, They Won't Come." [The presentation is available here: http://www.scribd.com/doc/39279251/David-Einhorn-Short-St-Joe]
The thesis was evidently persuasive; JOE's shares dropped ~20% shortly after Einhorn's speech.
I have no idea what this is indicating.