Wireless landscape in the U.S. is very unique where both GSM/UMTS and CDMA/1xEV-DO technologies thrive. With emergence of mobile broadband access technologies such as WiMAX and LTE on the horizon, major U.S. operators all have announced their strategies for path forward to remain competitive in the mobile service market. In parallel, the IP Multimedia Subsystem (IMS) has firmly taken its position since 2006 as the common service architecture for next generation networks including both fixed and mobile accesses. Nevertheless, the rollout of IMS is not as fast as its standards development and more operators' commitment is seen on fixed networks than on mobile networks. This paper first presents a perspective of future U.S. wireless landscape in terms of major operators' strategy in supporting mobile broadband services. It then discusses the current status of the IMS rollout in the U.S. including the deployment issues in mobile networks and the deployment situation in fixed networks. Finally, the paper concludes with an analysis of important issues in the future development of mobile broadband and IMS.