Delivering Rich User eXperience (RUX) with the current explosion of smartphone as real ubiquitous computing device requires adaptive application architecture. Rich Mobile Application (RMA) is likely the candidate architecture for future mobile applications to deliver rich, immersive experience to the smartphone users. Research and development in domain of RMA has started and results are appearing in literature which advocates its future trend and encourages review of RMAs. This article aims to present overview of RMA and states clear distinction between Rich Internet Applications (RIAs) - that are desktop-like Web applications - and RMAs to facilitate and accelerate development of smartphone-centric application development tools and technologies. RMAs are defined, their comprehensive overview is presented, and current trends are described. Our study shows that despite of literal similarity of RMA and RIA, they have dissimilar inward architectures. Implicitly, understanding the distinctions between richness delivery in PCs and smartphones as well as knowledge of inward similarity and difference between RIAs and RMAs contribute toward development of enhanced smartphone's applications to deliver RUX to mobile clients.