Scientists at Princeton University have managed to coax bacteria to behave like computers, assembling themselves into complex shapes based on instructions stuffed into their genes. This remarkable feat was achieved by a team led by Ron Weiss, and was published in April 28 issue of the journal Nature.
The research can lead to applications in detecting chemicals, nano-assembly, and full-scale biological computing. It might also lead to techniques allowing spontaneous assembly of new organs :).

Heart from Bacteria! (Courtesy: LiveScience)The 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 heart pattern, for example, around central cells based on communication between the bacteria. Other patterns included a bull's eye, and a flower.
Plasmids are circular double-stranded DNA molecules, normally found in bacteria. The scientists modified the genetic code inside certain plasmids, and inserted them into the genome of the bacteria. The bacteria used these synthetic codes to generate proteins, which directed the bacteria to move in certain ways, depending upon where other bacteria were. The proteins achieved this by detecting signals (in form of other chemicals) from other bacteria.
Real-life applications are, of course, years or decades away. But this work does provide a template on which future research could be based. The possibilities are endless :):).