McAfee are starting to talk quite a bit about VoIP these days. A bit late in my opinion. I'm really surprised it's taken them this long to jump on the bandwagon, as this will become at least as big an industry as anti-virus/anti-spam, their core markets.
In fact, in the following PDF, McAfee themselves admit that the problem will exceed that of email SPAM.
VoIP related stuff starts at section 1:3 - page 5:-
http://www.mcafee.com/us/local_content/ ... e_0407.pdf