Advanced ticket sales for the Theatrical Version of Pocket Monsters Diamond and Pearl - Movie 2 - Giratina and the Sky's Bouquet: Shaymin will be available on April 19! Prices are 1300 yen for general admission and 800 yen for a child. It is currently unknown if a ticket sold in advance will include any special offers but past promotions usually have. Giratina and the Sky's Bouquet: Shaymin will be released on July 19, 2008 in Japan.
Source:
http://www.daitokai.co.jp/theater/ticket.html