According to The Wrap Kristen will be presenting at the 2012 MTV Movie Awards. Charlize Theron and Chris Hemsworth are also presenting.

Joining the couple in handing out the popcorn trophies to their fellow actors and actresses: Charlize Theron, Kristen Stewart, Mark Wahlberg, Chris Hemsworth, Mila Kunis and Michael Fassbender.
The show, which will air live on MTV from the Gibson Amphitheatre in Universal City, is once again allowing fans to choose the Movie of the Year winner, with voting open at MTV.com and continuing through the broadcast on June 3.

Kristen will be presenting with Chris (Source):

Stewart, for instance, will be appearing alongside her "Snow White and the Huntsman" co-star Chris Hemsworth, who, by the way, is also Thor in the biggest box office smash in recent history, "The Avengers.

Via: vonch