If you're outside, they can't stop you. But if you're inside, trust me, you don't wanna do that.
I tried taking a picture of a sweater with my Tréo one day, while in store, and the little guard came up to me and told "Sorry ma'am. No pictures, please put your camera phone away." I was like WHY? I was telling him that I wanted t show one of my friends the sweater because I was interested in buying it maybe for their behalf but I would like that person to see it first. I was sooo by the way he told me to stop, that I just bought my Inclusion Speedy Keychain Black and left quickly. SoHo gives better treatment of its customers than 5th Ave.