Computing platforms are expected to be deeply embedded within physical objects and people, creating an Internet of Things. These embedded computing platforms will enable a wide spectrum of applications, including implantable and wearable medical devices, smart homes, smart meters, brain-machine interfaces, physical infrastructure monitoring, and intelligent transportation systems. Unfortunately, the explosion in devices and connectivity creates a much larger attack surface, opening up new opportunities for malicious people and entities. Unless significant attention is paid to security, the Internet of Things could well be turned into an Internet of "Things to be Hacked"! In this paper, we provide an overview of trends in embedded computing and highlight their implications on secure embedded system design. While embedded security is not a new topic, we argue that the characteristics and usage models of emerging embedded computing platforms necessitate a fresh look at embedded security and new approaches to secure embedded system design. We discuss the challenges using two case studies, viz., medical devices and smart homes. We provide examples of hypothetical and real security attacks, discuss the unique security challenges faced by these systems, and describe some initial efforts towards addressing them.