The Kroger system deploys Irisys thermal counters, which connects in real-time to the POS system in order to achieve reasonable predictive scheduling (how many cashiers to open in the next 10, 15, 20 minutes) and is considered a big marketing success for promoting customer service. Currently, there are only a few frontline management roll-outs, including ASDA (Wal-Mart UK) by Brickstream with video counters, Morrison's and Kroger by Irisys, and partial roll-out in Tesco (Irisys). Due to a marketing push by Irisys and Brickstream, there is a lot of interest by American supermarkets and in 2013 will probably see a pile of pilots.
Frontline management (or queue management for main banks) is not simple and requires expertise both in technology and deployment, but there are many advantages. Think in terms of having a security camera instead of a security guard; a 24/7 empiric system instead of objective observation by individuals. The more obvious benefit is customer perception, but there is also the optimization of active cashiers, real-time deployment, and real-time monitoring (instead of mystery shoppers), which generate money saving opportunities. Moreover, there is the 'soft' business benefit of using hard core data as basis of communication between corporate and the local store.
Long story short, video analytics has many benefits, from monitoring sales conversion, building schedules based on service intensity and service productivity metrics, in-store staying and browsing behaviors for marketing, queue management and predictive scheduling for the checkout process. Each market - retail, big box, supermarkets, airports etc. - has different requirements but the technology has evolved enough that we can start doing really interesting behavior analytics.