December sees yet another awesome addition to LittleBigPlanet 2 — the Cross-Controller Pack — making LittleBigPlanet 2 the first game to support this exciting new feature!

But what is Cross-Controller? Well, Cross-Controller lets you to use PS Vita as a controller for PlayStation 3, allowing the use of PS Vita-only features, like front and rear touch, in PlayStation 3 games. More importantly, it provides a whole second screen where action can take place! This allows for an unimaginable number of new ways to play, some of which you’ll experience with the LittleBigPlanet 2 Cross-Controller Pack!

In the LittleBigPlanet 2: Cross-Controller Pack, Sackboy joins up with a group of lovable Space Pirates as they race to find a valuable treasure long thought lost to the Cosmos. On their adventure they’ll encounter new obstacles that can only be overcome with the help of PS Vita’s unique features.

As well as a new adventure for Sackboy to take part in, players can get their hands on a suite of new tools that let them create Cross-Controller levels for the community to play.

The LittleBigPlanet 2: Cross-Controller Pack will be available via download on PSN Tuesday, December 18th for $4.99, and requires a PlayStation 3, a copy of LittleBigPlanet 2 and a PS Vita.

SOURCE:

http://blog.us.playstation.com/2012/12/12/littlebigplanet-2-cross-controller-pack-out-next-tuesday/

In short, it makes the PS3 a bluray version of the wii u.
Unnecessary but more is more I suppose.

Sort of. The Wii U gamepad will have its level of unique and it also has IR like the Wii Motes. While Vita doesn't have that it is still up in the air what each device can do technically. We won't really see much in cross controller until PS4 but it opens wide the door to Wii U and PS3/PS4/Vita multiplats. The move tried to do that but it came out too late. I can't wait to see what developers come up with having at least two consoles with a new controller option.

Honestly I don't think it offers anything other than a gimmick. We should be increasing immersion, not breaking it by screen hopping.