The ways in which scientists communicate with each other have changed dramatically in recent years. With the ever-increasing popularity of blogs and instant messaging, one might be forgiven for thinking that correspondence is becoming something of a dying art. However, this issue of Nature Reviews Microbiology proves that microbiologists can still be moved to put pen to paper (or fingers to keyboard) when the need arises. In our April issue we published an Opinion article by David Moreira and Purificación López-García, in which the authors argue that viruses are not living entities and should not be included in the tree of life. As you might expect for such a controversial topic, we have received a flurry of correspondence in response, and these letters, along with the reply from Moreira and López-García, can now be accessed online through the contents page for this issue.

Another area that has seen recent rapid technological progress is, of course, microbial genomics, with the emergence of new techniques such as whole-genome DNA arrays and high-throughput sequencing. One area in which these techniques could make an impact in the future is in the detection of genomic changes such as gene duplication and amplification (GDA). On page 578, Linus Sandegren and Dan Andersson discuss how GDA constitutes an important adaptive response to antibiotic stress.

Finally, on page 555, Michael Otto gives an excellent overview of our knowledge of the virulence of Staphylococcus epidermidis. S. epidermidis is among the most frequent causes of nosocomial infections. Yet, as Otto discusses, this organism has evolved as part of our commensal skin flora and should therefore be viewed as an 'accidental' pathogen. Otto discusses the molecular basis of the commensal and infectious lifestyles of S. epidermidis, and what tips the balance towards pathogenesis.