No, ALL the iMacs are 16:10 AND ALL the Cinema Displays are too.
The iMac 24" is bigger vertically AND horizontally than the 23" display 😛
16:10 is slightly squarer than a 16:9 movie, buy computer displays are not generally 16:9.
(Trivia note: all Apple widescreens have been 16:10 EXCEPT the PowerBook G4 series which were 3:2.)