What was revolutionary was that a trusted source of shooting high quality digital still images now began shooting movies. Many film-makers embraced this new medium and nearly half a lakh cameras (50,000) were sold in a few months.
Then came the Canon 7D which could shoot '24fps', 25fps, and '30fps' movies. But this camera had a smaller sensor so less depth of field than the 5D Mk II. Then came the Canon 1D MkIV which could shoot is extremely low light also at '24fps', 25fps, and '30fps'. But this camera too had a small sensor.
Now, finally with this new firmware, the 5D MkII with its 'full frame' sensor will do '24fps' and film-makers will achieve that depth of field, and colour fidelity that only the 5D can provide.
Two small asides.
'24fps' in all these cameras is actually not 24fps but 23.98 or 23.976 fps. In the NTSC world its no matter because they use 23.98 fps more often than 24fps. Because 23.98 fps converts to their TV's 29.97 fps more cleanly than does 24fps.
But in the PAL world we use 'real' 24fps only for film. Our TV is 25 fps. This small 23.98fps vs. 24fps difference is no real problem. You can shoot 23.98fps and use CinemaTools to make it 24 fps.
The other thing is about depth of field. Even though the Canon 7D and the Canon 1D MkIV have a smaller sensor than the so-called 'full frame' sensor of the Canon 5D MkII, this small sensor is still as large as a 35mm movie frame. So the 7d and the 1D MkIV will give you depth of field equivalent to that of a 35mm movie camera.
The Canon 5D MkII has a sensor that's the same size as a 35mm still film frame not 35 mm movie film frame (like in a Arri 535/435). So, it actually delivers depth of field far shallower than any movie camera can provide or movie cinematographer is used to seeing. Few know or realise that a 35mm still film frame is twice the size of the 35mm movie film frame.
36x24mm for 35mm film still frame vs 24x18mm for a 35mm movie film frame (Super35 or Academy).
So, just to get more technical...
36x24mm has a diagonal of 43mm
24x18mm has a diagonal of 30mm
And since, diagonal dictates 'normal' focal length, and focal length decides depth of field, a 35mm still frame has a shallower depth of field than 35mm movie frame.
The point is, those who lamented about the depth of field of the 7D vs the 5DMkII while pining for 24fps in the 5D, can now have the best of both with the 5DMkII with '24fps' firmware. Coming soon to a Canon near you. What will be interesting is how this affects the sale of the 7D and 1D MkIV vs the 5DMkII.