I'd like to put my hand up to be part of the VoIP SIG.
After mentioning this in IRC, I've also had two other people contact
me privately (puzzled and JHogarth) with their interest too.
Currently we (FreePBX) build 'FreePBX Distro', which is a up-to-date
CentOS distro, with a couple of known-broken packages upgraded (drbd,
pacemaker) or replaced (asterisk).
--Rob