The 40th Anniversary Kamen Rider movie presentation is finally confirmed! It will be entitled OOO - Den-O - All Riders: Let's Go Kamen Rider, and scheduled to be shown on April 1 of 2011.
Aside from being a 40th Anniversary Kamen Rider movie, OOO - Den-O - All Riders: Let's Go Kamen Rider is also said to commemorate the 60th Anniversary of TOEI.
And aside from the titular Kamen Rider OOO and Den-O, OOO - Den-O - All Riders: Let's Go Kamen Rider movie will feature Kamen Rider 1. This would be his first decent Kamen Rider appearance after many years which is not a cameo. The story will involve traveling through space and time to Kamen Rider 1's World, and it appears that all of the past Kamen Riders will be making an appearance.
As for rumors circulating a few weeks ago, original actors for Kamen Rider Kabuto, Den-O, V3, X and Black will each reprise their roles. Although as of now, nothing is confirmed.
According to NeonZ of HJU, there have been some rumors regarding the staffs for the OOO - Den-O - All Riders: Let's Go Kamen Rider movie which includes Kenji Konuta, writer of Kamen Rider Decade's Kabuto World, as the writer; Yasuko Kobayashi (Kamen Rider OOO, Kamen Rider Den-O, Kamen Rider Ryuki) for setting cooperation; and Taro Sakamoto as the director.
In addition, the official site for OOO - Den-O - All Riders: Let's Go Kamen Rider movie opened last December 18 and features a teaser for the movie.
Source: Sponichi Annex