There appears to be an increase in p2p communication among botnets that has been attributed to the sirefef/zeroaccess malware botnet. What is known on this particular threat?
See http://techchannel.att.com/play-video.cfm/2012/8/31/AT&T-ThreatTraq-SIfref-DVRbot-Internet-Weather for a video blog on this. Looking at AT&T's 'internet weather', the activity was picked up and they give an analysis of what they found.
The kindsight blog also has information at http://www.kindsight.net/en/blog/2012/06/28/malware-analysis-new-cc-protocol-for-zeroaccesssirefef