As part of LA Art Weekend, which runs through Sunday, the Storefront for Art & Architecture of New York City opened their first of many worldwide temporary pop-up stores in Los Angeles last night. What are these pop-up stores? Well, they are becoming quite ubiquitous, albeit in spurts, around the city. Trendwatching.com rhetorically answers: "If new products can come and go, why can't the stores that display them do the same?" The show at Paperchase......