On Thursday August 4 from 17:00 - 20:00 Eastern Time (5:00 PM - 8:00 PM), Rockstar is hosting a Social Club Multiplayer Event. Please see my calendar blog post for a full Calendar of known events with a time zone converter and a description of the Social Club events.
Rockstar has announced that Triple XP will be extended after the event all Thursday night and into Friday morning.
Although the official event is being held for Xbox only, both platforms get Triple XP. The next event for PSN will be Friday, August 26.
The main contest prize during this event is two custom Red Dead Redemption hand painted Xbox 360 controllers. Even if you can't participate in the event, you can stop by the Social Club Multiplayer Events page to enter the contest. 20 Rockstar prize packs are also being given away.