I don't think wearing tac gear (vests, rigs, holsters, etc) is really appropriate (or necessary - it's easy to remove) in public... but as far as BDUs are concerned, I commonly wear half/half on ordinary days. And as someone mentioned, camo is "in" these days, so nobody thinks twice about it. (I started seeing a lot of people going around with 3 color desert lately, so I started wearing mine, too. Woo! At last I'm one of the trendy kids!)
And to expand on Black_Orchid's comment, I think most civvies don't know the first thing about camo anyway. I regularly wear my DPM smock in spring/fall, and have on many occasions had people comment "you're in the army?" Hell, when I worked at the surplus, 3/4 of the people who came in didn't notice US woodland and DPM weren't the same pattern until I pointed it out.