credit: Planet Megaman ( http://www.planet-megaman.com/ ) , Rockman Perfect memories
Go here for the trailer: http://rockman.hosthelpers.net/
Just saw the trailer myself, Inafune really knows what hes doing with each game
Now how about Zero 5 on the DS or PSP? 
Go here for the trailer: http://rockman.hosthelpers.net/
Rockman Perfect Memories has updated including links to a Rockman Zero 4 video wich mostly includes scenes of mostly gamplay which boasts the amazing amount of original, awesome stages, the "Weapon Seizing System", the "Weather Changing System", the new Cyber Elf System, the parts for customizing Zero's Head, Body and Foot, and collecting enemy parts such as the Laiken's chassis, a spring from the Cannon Hopper, the arm of the Shift Cannon, the Flottan's CPU, the chassis of the Ice Tank, the Yadokaroid's hull or even a Gyro Cannon's Core (among many other things to collect and use to make new weapons and items).
Boasting cool features is not all this video has. It also has a really cool background theme playing that may very well be a theme right from Zero 4. Also, the video shows boss battles with various bosses, some we have prior to this not yet seen. Witnessing these, it seems this time we may face the most intense and hard action boss battles we ever have. To see what I mean, I highly recommend you take a look at the video, and be amazed with all that Zero 4 has to offer still 21 and a half days before its release.
The game is still scheduled for Thursday, April 21st 2005, and this Spring, Everything Will Become Zero.
Just saw the trailer myself, Inafune really knows what hes doing with each game