DICE has announced the first double XP weekend for Battlefield 3 and it's starts tonight. Starting from midnight PST tonight to midnight PST, Sunday, May 13 with all classes of soldiers receiving twice the usual experience.
The announcement will probably be a little awkward for some given the recent controversy EA has caused by apparently removing free servers from Battlefield 3. That report has since been debunked by EA.
EA also recently held a double XP weekend for SSX. I expect them to adopt these across all applicable titles and surely Mass Effect 3 can't be very far off from getting it's own as well.