Warcry has a super interesting reading of the XP leveling changes that Blizzard is making in 2.3. Their style is a little more, err, informal than ours, but they're right-- Blizzard is basically stealing XP from you in the next patch. Vaneras confirmed the other day that players who have a certain percentage of XP before the patch will keep that same percentage of XP, but not the same amount of XP. So, if, for example, you're halfway through level 59 when the patch hits, you'll lose about 600,000 XP that you've already earned.
But before you get all angry about Blizzard wasting all that time you spent leveling, realize that things will likely even out in the end. Even though you'll lose 600,000 XP from the amount you have, you'll still be halfway through level 59, and you won't need as much XP as you did before to level to 60. So you haven't really "lost" anything, because even though Blizzard has "taken away" some XP, you didn't need what they took anyway.
As we've said before, these leveling improvements are going to be great news, not only for altaholics who are leveling up their third or fourth character by now, but also for guilds eager to see some new 70s to bring into the raiding mix. Folks who are leveling both before and after patch 2.3 are going to experience some strange math, but that happens all the time anyway (did you know that all the stuff you're killing at level 70 now doesn't count towards the experience you'll need to earn in the next expansion?). Blizzard is tweaking the numbers, but the experience will still be faster.