According to Mihara's blog (Mihara being the driving force behind recent PS2 Cave ports DoDonpachi Dai-Ou-Jou and EspGaluda) the rumored Ketsui DS is indeed very real and about to hit the DS in Japan. The game will be playable at the annual Cave festival held HEY in Akihabara. Here's a short video of the game posted by Mihara.
So far it looks good. It's obvious the graphics and bullet patterns were toned down quite a bit. However, speculation continues to run rampant. Will it have difficulty settings? Tate mode? Is it a boss rush or the full game? We'll have to wait to find out.
here's another video, this one of the demo available at kiosks in japan.
Next up is the identity of Treasure's new DS game : Bangai-O Spirits. No info available as of yet, though the webpage has gone from an intro and a splash screen to a picture of a robot and a logo (another splash screen.)