Facing great challenges in designing better assistive technology with ever more complex and pervasive IT systems we need a general change in our understanding of designing IT. Ways to improve the performance of IT without drowning in complexity are of prime importance. This paper presents bio-mimetic design of Ambient Intelligence as a candidate heuristic for the task. It is shown how better assistive functionally goes hand in hand with improved infrastructural capacities by mimicking natural complex systems. On the basis of a presentation of organizational and developmental issues addressed by modern biological models we will suggest preliminary design constraints for Ambient Intelligence ecologies.