According to FilmThrasher, DreamWorks has moved the release of How to Train Your Dragon 2 one week ahead of its previous release date, June 20th. This will put it up against 22 Jump Street, which means Jonah Hill will have one exciting weekend.
In addition, Christopher Mintz-Plasse said this about the sequel in an interview two days ago:
It’s crazy man, we have Cate Blanchett [voicing Valka] in this one now, who’s killer. And something really dark happens in it, it’s gonna hit that emotional point. It’s gonna be good. It’s gonna be really good.Thanks, hope-for-snow!
UPDATE: It's seems possible that FilmThrasher was either misinformed about the release date in their article. It's unconfirmed by DreamWorks, so take this new information with a grain of salt.
UPDATE 2: FilmThrasher gave us its source. Box Office Mojo and ComingSoon.net confirm this date as well, though kris0ten says the release date is unchanged.
UPDATE 8/20: June 13th has been confirmed as the new date! Thanks inhonoredglory!