Two companies piqued my interest while touring the exhibit hall. I am not a huge fan of blocking software but reality requires it. We need to improve ours to be more granular, so that kids can easily move between different levels of filtering depending on their responsibility.
One is Cymphonix. They have a 2 year old mac client with LDAP. It is an inline box that does packet shaping. Very similar to DeepNines. He was non committal about pricing.
The other one was cipafilter.com. This works as a proxy server with locked down browsers. The difference between this and our current squid proxy is that filtering settings are based on LDAP groups. We could just move kids in and out of groups in workgroup manager to change their filtering status.