Camiant uses GPL-Linux at the heart of its Broadband Policy Controller, which it's selling to cable systems who are also ISPs. A Camiant official named Adam Smith (that was his name) explained how a Broadband Policy Controller is at the heart of a good IP Media Subsystem (IMS).
What does it do? For one thing it can provide QoS (Quality of Service) for the ISP's customers. Say a kid is running an online game that requires low latency, or you need high quality in your Voice over IP connection, or you just want to assure that a video stream comes through in real-time.
QoS matches the bits' port destinations to your policy, and gives the bits that need it a fast path. It sounds innocent. Assured bandwidth, packet priority and low latency are qualities some applications really need. Smith noted Camiant also makes Web-based software that lets customers order these enhanced services as they need them, which sounds nifty.
On the other hand, a Camiant cable customer might also offer this QoS service to the other side of the transaction -- to the game company, to the VOIP company, to the outfit promoting the video stream. It could choose to give some of these companies priority over others, disadvantaging some Internet products and services at the expense of others. "You got some nice bits there, it would be a shame if something happened to them."
This is the heart of the network neutrality debate. In fact, this is the innocent edge of it, because there are good, sound reasons why you as a customer might want these capabilities. But if they're not offered equally to every vendor, or not offered at a customer's sole discretion, you are talking about a potential evil.
A cable ISP could use this power to favor big companies (that can pay) over small ones (that might become big if the playing field is level). Suddenly the fast evolution and social mobility the Net ushered in starts to fade.