According to Newtype March issue, Mobile Suit Gundam 00 Movie was announced to be premiered this September.

Source: Scan of Newtype

Updated on March 25th
According to Movix, the premiere date is September 18th.

Source: Movix

Premiere Dates of Anime Movies This Year
Feb 20 Mobile Suit Gundam Unicorn
Feb 27 Keroro Gunsou Movie 8
Feb 27 SD Gundam Sangoku-den Brave Battle Warriors

Mar 06 Eve no Jikan (movie)
Mar 06 Doraemon Nobita no Ningyo Daikaisen
Mar 20 Eiga Precure All-Stars DX 2
Mar 13 Higashi no Eden - Movie II: Paradise Lost

Apr 17 Crayon Shin-chan Chojiku! Arashi wo Yobu Ora no Hanayome
Apr 17 Detective Conan Movie 14: The Lost Ship in the Sky
Apr 24 Trigun: Badlands Rumble
Apr 24 Gintama: Shinyaku Benizakura-hen

May 01 Bungaku Shoujo
May 01 King of Thorn
May 29 Break Blade I

Jun 05 Hetalia Axis Powers the Movie
Jul 17 Karigurashi no Arrietty
Jul 31 Konchuu Monogatari Minashigo Hutch Yuki no Melody
Aug 01 Naruto: Shippuuden Movie 2010
Sep ?? Mobile Suit Gundam 00 Movie

Summer Uchuu Show e Youkoso
Summer Metal Fight Beyblade Movie
Summer Colorful
Autumn Macross Frontier ~Sayonara no Tsubasa~
Winter Bleach Movie 4