Eventcore plans and executes large events and meetings like 2013 AT&T developer summit (http://www.whois.com/whois/2013devsummit.com) and they only acquire domains for events they are organizing.
They also have MS in their list of references. (e.g. https://microsofthostingsummit.com/)
But especially this:
www.xboxe312.com (google cache) - official site for media registration for E3 2012 Keynote
This event is also managed by Eventcore and the domain was acquired also by them.
Now we compare both sites:
Xbox event around the corner?