Cherry Blacks (Sold on EliteKeyboards as 'Linear Force')are considered to be good gaming because -
a) No 'bump' (i.e. tactility) on the way down, it's a smooth linear switch.
b) They're quite stiff, so that prevents accidental keypresses.
Of course, the above two reasons also make them unpleasant for touch typing - the high force can make it tiring and slow for touch typing, and the lack of a clearly defined tactile point makes it hard to know when the key has been registered.
A better compromise may be the Cherry Browns ('Tactile Force') these are low-force switches with a subtle tactile point. They're good for doing alot of fast typing, and because they don't offer a lot of resistance, they'd be good for gaming as well. Only problem is that a lot of people find them almost too light, they can take a while to get used to.
As for the Cherry Blues, they're a nice switch for typing on, but as much for gaming on. They have a noticeable tactile bump, and this interferes with repeated keypressing in games. It's hard to describe, but you'd notice it quite quickly if you were doing something that required you tap a button repeatedly. Basically, if you want to a press a button more than once, you have to let the key come all the way back up before pressing it again. Theyre not completely unusable, but if the main purpose of the board is for gaming, you'd be better off with one of the other two.