I'm with everyone -- I use both.

I carry a small P&S for those times when I prefer to be unobtrusive, or don't want to carry a big SLR (such as when photography isn't the main purpose of going out). My P&S is waterproof, too, without the need to spend a thousand bucks or so on a housing. But the lens is crap, and there are few manual controls.

On the other hand, my SLR is more versatile in low light situations, has a greater degree of variability with regards to lens choices (I've rented lenses in the past), has manual controls, is faster, and takes better pictures in general. But it's bigger, more obvious, and not appropriate to carry everywhere.