From 2010, but hey, it's still important:
"In the latest exploration into the universe of organisms inhabiting our bodies, microbiologists have discovered new viral genes in faeces. They find that the composition of virus populations inhabiting the tail ends of healthy intestines (as represented in our stools) is unique to each individual and stable over time. Even identical twins — who share many of the same intestinal bacteria — differed in their gut's viral make-up."
And I like this comment:
"In oceans, the modality of viruses has tended to be predatory," comments Edward DeLong at the Massachusetts Institute of Technology in Cambridge. "Now the interesting thing here is that the system in the faecal microbiota seems to be driven by prophages, which tend to basically integrate their genetic material into the host genome and hide there — it's a much more stable situation."
Thanks to Paul Kennedy in my lab, who reminded me of this.