(agreeing with no1mad...) yeah, 23mm and 25mm is pretty much road racing bike territory. even the Tour De France riders were on 28mm for some of the rougher and longer stages this last year.
I personally wouldn't go skinnier than a 28mm on a hybrid street bike, and right now I'm pretty happy on 35mm as they let me ride on dirt roads without feeling like I'm gonna get tossed sideways if I clip a small rock.