Bacteria engineered to secrete toxin that kills harmful bacteria
Using the tools of synthetic biology bio-engineers have created a strain of E.coli that detects the presence of a pathogen then releases a toxin that specifically kills that pathogen
Scientific American: 16 August 2011
TechNyou
Apparently this is the first time people have tried to use synthetic biology to fight infection. The full paper is available. The authors do describe what synthetic biology is and why their research can be defined as synthetic biology. What I am unsure about is if the genes they use to build this E.coli are synthetic (ie not found in nature) or exist already and they have just done a bit of plug and play. Feel free to enlighten me.

All the genes used in this project were originally sourced from nature. However they have been extensively altered (edited) , and some have even been assembled from parts of natural genes.
Cool, I am now prepared to say that the research can be defined as synthetic biology. Jason, TechNyou