HealthVault has no notification mechanism. So there is no way say your users can see there images automatically updated in one browser window if the other one upload one. One can do this my polling the PersonalImage data-item for the LastUpdated time stamp. If the time stamp is greater than the last time we got data from healthvault then re-do it or this all could be buried under a cache manager. Something like
PersonalImage pItem = new PersonalImage(); pItem.LastUpdated;
In the HealthAndFitness application provided in HealthVault SDK, we provide a single click mechanism where the user can referesh all site data, perhaps something like this could be used to refresh the image or other individual data-items as well.