The latest issue of Cell has some goodies on synthetic and systems biology: "Engineering Static and Dynamic Control of Synthetic Pathways, by William Holtz and Jay Keasling:

Maximizing the production of a desired small molecule is one of the primary goals in metabolic engineering. Recent advances in the nascent field of synthetic biology have increased the predictability of small-molecule production in engineered cells growing under constant conditions. The next frontier is to create synthetic pathways that adapt to changing environments.

And Luis Serrano, with Christina Kiel and Eva Yus, review The Engineering of Signal Transduction Pathways:

In principle, in order to create fully artificial living systems that are able to respond to their environment, evolve, and reproduce, we first need a deep level of understanding of how cells work. However, we are still far away from reaching this goal. Systems biology has contributed significantly by uncovering many general systems properties, such as feedback regulation and noise. Further, large-scale experiments have revealed genetic and protein interaction networks in different organisms. However, our understanding is incomplete concerning the cellular functions and regulation of all proteins, and how cells adapt to a different environments.... There have been many discussions on whether there is a limitation to what we can learn about biology. Although there will always be something new to learn about biological systems, like other disciplines of science, the pace of discovery may eventually slow down. On the other hand, provided that we have the tools, the engineering of living systems appears to be limited only by our imagination.

If you want to know where the field is right now, check out these pieces. Read the feed: