I voted "yes," but really, I don't let her walk all the time. She LOVES to walk and explore the store, and I do feel like it's good exercise (sometimes the only walking she gets during the day

). She was "walking" holding on the cart ("helping me push") before she turned 1. However, she has a VERY poor radar for proximity to other people. One day in the library she almost knocked over a very old lady with a cane.
That was a sobering experience. She also touches
everything. I understand how tempting the store must be (it is designed to be tempting, to know), but wow-- the constant supervision wears me out.
Usually, if I have the patience, I start off by letting her walk. We talk about our rules beforehand, and if she breaks the rules, she goes into the sling or the cart.
She's an only child right now, though. When her little brother is born, I think she will be spending a lot more time in the cart.... or, if all my dreams come true, she'll be helping watch her little brother at home with her father while I sip Starbucks and shop by myself. As much as I enjoy being with her, our grocery budget is tight and I simply cannot focus adequately while keeping up with her/keeping her quiet/entertaining her.... So we're about to start trying a new grocery plan which basically involves her not being there until she's older and has a little more self-control.