On Friday April 20 from 16:00 - 19:00 Eastern Time (4:00 PM - 7:00 PM), Rockstar is hosting a Social Club Multiplayer Event. Triple XP will be active throughout the weekend. Although the official event is being held for PS3 only, both platforms get Triple XP.
During the event, Social Club members can enter a drawing to win a pair of custom PS3 controllers or one of twenty prize packs (t-shirt, RDR playing cards, and stickers) - follow the above link for details.
The remaining Social Club events that have been announced for May and June are all for Max Payne 3, since that game is being released next month. In 2011, the majority of Social Club events were for Red Dead Redemption, but the earlier games Grand Theft Auto IV and Midnight Club: Los Angeles also had occasional events. Although nothing has been announced yet, I suspect that in 2012 the majority of events will be for Max Payne 3, while Red Dead Redemption will have an event every couple of months.