"Bacteria have been programmed to behave like computers, assembling themselves into complex shapes based on instructions stuffed into their genes... researchers programmed E. coli bacteria to emit red or green fluorescent light in response to a signal emitted from another set of E. coli. The living cells were commanded to make a bull's-eye pattern, for example, around central cells based on communication between the bacteria. Other patterns produced with this new "synthetic biology" technique include a pretty good semblance of a heart and a rudimentary flower pattern."

(via)