The US Senate is debating S 2917: Internet Freedom Preservation Act, which would prevent ISPs from giving preferential treatment to content providers that pay. They are also debating S 2686: Communications, Consumers' Choice, and Broadband Deployment Act of 2006, which would greatly reform telecommications laws and allow for a tiered Internet.
Apparently, telecom providers want to compete with cable television providers, and they want content providers to subsidize their effort. The first bill mentioned above would seek to prevent that. The second would facilitate it.
For a really well-fleshed out article on the subject, check out "Speed Bumps on the Information Highway," by Tom Abate, Chronicle Staff Writer. This FreePress page provides more arguments in favor of Net Neutrality.
I recommend this sarcastic article, called "Net Neutrality Has Ruined the Web," for those who understand something about electronic communications.