Google announced that they've upgraded the events based knowledge graph to show official ticket links, comedian events, venue events and delegated events sites. They also upgraded the developer site to document much of this.
(1) Official Ticket Links lets the knowledge graph add data such as on-sale date, availability, and a direct link to your preferred ticketing site, such as TicketMaster:
(2) Delegated Event Listings for those of you who do not have this type of data on your site, you can reference another site where it can pull the data. You can do this using the delegate site markup.
(3) Venue Events, where Google will show you the events at a specific venue, such as Concert venues, theaters, libraries, fairgrounds, etc:
(4) Comedian Events where comedians are now considered artists by Google and they can show up in this knowledge graph as well.
Forum discussion at Google+.
