Regarding the hub package (cfengine-nova-hub), the current version (Enterprise 3.5.1) of Debian 6 is running fine on Debian 7 machine. There was a PHP compat problem on 3.0 but since we compile everything and package up on our own, we have managed to get rid of this incompatibility problem. Please feel free to use the package and run on Debian 7 machine.
You may download packages from here,
Enterprise Software Download,
https://cfengine.com/software
** THIS was fixed on Enterprise 3.5.2 ***
CFEngine system variables $(sys.flavour) and $(sys.arch) on 3.5.0/3.5.1 were translated incorrectly. If you intend to use CFEngine automatic client upgrade to upgrade your managed nodes, you may need to rename these directories from;
"/var/cfengine/master_software_updates/debian_7_i686"
"/var/cfengine/master_software_updates/debian_7_x86_64"
to
"/var/cfengine/master_software_updates/debian_7 \n \l_i686"
"/var/cfengine/master_software_updates/debian_7 \n \l_x86_64"