A lot of information was revealed at The Legend of Korra panel at San Diego Comic Con and they are summarized in this news article.
Some highlights from the panel include:
Book 2 is titled "Spirits" and takes place 6 months after Book 1.
Korra, Mako, Bolin and Asami will be wearing new costumes.
Pro-bending will still be featured in Book 2. Mako and Korra are no longer part of the Fire Ferrets but Bolin has picked up two newbies to form the new Fire Ferrets. Footage shown at the con revealed the new team facing off against the Elephant Lions but they fail miserably.
Mako is now working as a policeman in Republic City. Footage at the con showed him chasing after some crooks on a motorcycle.
Asami is now the head of Future Industries. Footage at the con showed that they have branched off into selling planes but Asami is a little worried about making the company reputable again since her father tarnished its name.
Korra will be traveling into the Spirit World. She will be learning more about her spiritual side.
We will be seeing more of Korra's parents as well as her expanded family.
Kya and Bumi, Avatar Aang and Katara's eldest two children, will be featured more in Book 2.
Pictures and information have been put on tumblr and tweeted live during SDCC. The links to those twitters and tumblr blogs have been linked here so do check them out! I recommend going to Owl's tumblr for pictures of the lovely concept art!
Edit: Two posters were given out at the signing today. One poster is titled "Old Friends" which has grown up Aang, Katara, Toph, Zuko, Sokka and Momo while the other poster is titled "New Friends" which has Asami, Bolin, Korra, Mako and Tenzin.
In addition to that, individual badges of Korra, Asami, Bolin and Mako were also given out by Nickelodeon.
Special thanks to ASNer The Tea Weevil for these pictures!
Edit 2: MTV Geeks interviewed Bryan Konietzko, Mike DiMartino, Janet Varney, David Faustino, PJ Byrne and Seychelle Gabriel at SDCC regarding the show. The interview is quite entertaining and interesting to watch.
This post has been edited by Luka211 on 14 Jul 2012, 20:48 
The Last Airbender: The Legend of Korra, ლეგენდა კორაზე
