Quote from IGN:

Destiny's exclusive PS4 and PS3 content will be coming to Xbox One and Xbox 360 at some stage in the future, according to a retail listing.

According to Amazon, the unique weapons, maps, ships and gear "will only be on PlayStation until at least Fall 2015". While not a guarantee by any means, it does seem that Activision's shooter will contain timed-exclusives rather than outright ones.

Right at launch, both PS4 and PS3 players will get a unique co-op strike mission on Mars, a competitive map, a bunch of exclusive guns, gear, and three ships.

Bungie is going big with Destiny, the first game from the studio since it parted ways with Microsoft and the Halo franchise. And Activision believes in the MMO first-person shooter, putting $500 million into the game’s development and promotion. We recently talked to the developer about how it came up with the idea, initially wanting to stay as far away from anything Halo-like as possible.

We've reached out to Activision to see if we can get confirmation on the above and will update the story when we hear back. For much more on Destiny, be sure to read our latest in-depth preview from E3 2014.

Source: http://ca.ign.com/articles/2014/06/20/destinys-ps4-and-ps3-exclusive-content-to-last-until-fall-2015

I would not be surprised if the Japan exclusivity would also be a timed exclusive. Not like it would change anything regarding the success of the Xbox One in Japan anyway :) In any case, this is a good news for Xbox owners!

A whole year?? Damn! I was expecting it to be less given the nature of a lot of timed exclusive content.

1 year of timed exclusivity for some DLC is pretty long, if someone wants that content then he'll get the game on PS4 nobody, that really wants that stuff, will wait a year for it.

Very smart marketing deal Sony has made with Destiny.

It's not like there is really anything there though that is necessary or even worthwhile except the 1 mission and map. I would presume DLC will be 1 month timed exclusive like CoD 

I do not see anybody buying a PS4 over that small content if they already have an Xbox One/Xbox 360.

Actually, I'm surprised it is not a all-time exclusive, knowing how Sony was marketing the game like it was a Playstation exlusive game. But I agree, it shows that Sony played it well with that one at least.

That's true. The "exclusive" content argument does not sway me. I buy on the platform I like. Timed exclusive content on the Xbox never bothered me, and even the exclusive Fifa content on X doesn't phase me. The AC stuff on PS have been hit or miss as well.As long as the core game is intact and the game runs well then I'm in. If it's technically inferior to the version on another system, especially framerate and tearing, then I might have an issue.

Either way, I'm a little surprised this stuff will only be available for at least a year.

No, that I don't see happening either, but if you want to get a console for Destiny then there are a lot of reasons to pick the PS4, especially that beautiful white PS4 bundle.

That should help people choosing between two consoles though

I will buy the game (and play with my friends/kids on Xbox One) but eventually, like any generation, I will end up buying the PS4; this while bundle is atractive, so even if I have the game already on another platform, I may endup buying it just for the white console!

And people thought MS were bad for getting COD DLC 1 month early lol