It doesn't have to be multiple stores. It could still be one store just like OVI is and support multiple platforms which OVI does. As far as a developer doing uploads it depends if they want to support multiple chipset architectures and/or devices. Qt is the common denominator so currently you would only have to compile for ARM or x86 (i.e. you could compile once and support Symbian and the N900) assuming you have the necessary ifs for differences.