The Bungie demo for Destiny showed how players can join a public event, easily.
The sci-fi shooter demo took place on a deserted earth in the far future where a walled city is present. Players fought with Fallen enemies, grabbed loot which varied by character it seemed, and just showed how cool it looked in general.
Reminded me of Borderlands meets Halo, and I wasn't the only one who thought so.
Destiny out in 2014 and Sony has secured a long-term exclusivity deal for the franchise. This will enable both to grow together over the years.