Comcast has conducted their first major trial on P4P technology - a new more efficient peer-to-peer protocol being developed by a coalition of ISPs, researchers and Pando networks - and the results point to a massive improvement in network usage and download speeds. Specifically, the tests involved a 21MB media file and "iTracker" servers, which provided an 80 percent speed boost for users while heavily reducing the amount of inbound and outbound traffic for the cable provider.
The new system works by localizing peer-to-peer file sharing, instead of just downloading or uploading data from and to people all over the world, so that peers within an ISP's network are prioritized and data is routed internally across such network when possible. This is actually expected to (slightly) increase an ISP's local network traffic, but the real benefit comes from cutting the financial hit they take from sending traffic over transit links.
While these initial findings look promising, it is important to note that this was only a preliminary test and surely there will be other important concerns ISPs will want to address before making P4P use widespread, such as anti-piracy measures and filters.