The latest promotion began yesterday and will run through the server maintenance period on June 29th. For this event, the defensive buffs in Heiron and Beluslan have been removed (but they're still up in Eltnen and Morheim). In other words, if you're looking for high-level rifting action, now's the time.
As far as the AP portion of the event goes, you'll earn more and keep more. AP loss from PvP deaths in the Abyss and Silentera Canyon has been cut in half, and monsters in both zones will reward more AP per kill (though NCsoft's website blurb doesn't say exactly how much). In short, now is a great time to check out all the changes courtesy of 2.5, and we'd love to read about your reactions in the comments.