Apple’s first retail store in San Francisco will open on Union Square at One Stockton Street on February 28, just two days before the March 1-3 PhotoshopWorld Conference & Expo in the nearby Moscone Center. PhotoshopWorld officials plan to capitalize on the convenience of the two dates with a special offer: buy an item from the new Union Square store and you’ll receive US$100 off the PhotoshopWorld conference registration price — or free admission to the expo hall.