Well, it seems that today's maintenance brought about a massive change to Arena Point calculations. It's unfortunate that this change wasn't mentioned previously, and people had to find out about it when logging in to possibly get their new items.
The players most effected by this are the ones with extremely high ratings; the ceiling for point gains was lowered by nearly 1,000 points, though the rating required to reach that number of points remains the same.
I'm honestly not sure as to why this was done; the arena season has gone on longer than Blizzard initially intended, and as such, they saw top-end teams fully equipped, and must have panicked. The point system as it was worked out fairly well, and allowed the top teams to progress through their items at a pace that seemed fitting for being the best team(s) on a Battlegroup.
This new change is going to slow down progression at the top, and have a minor negative impact for teams with sub-1500 ratings(where the majority of the impact should have been felt - not at the top).
You can find the confirmation posted by Eyonix on the WoW forums.
To give an idea of the comparison between the new and old point calc systems, frals from quakenet created a graph depicting the two.
He's also created a point calculator using the new equation, which you can check out here. It only works for ratings over 1500, but you can plug in your rating to see the estimated point values you'll receive under the new system.
Sibbor also created a point calc, found here, that works with any rating value.