David Weinberger has a post up about the importance of internet neutrality and links to Save The Internet; Free Press also has a Net Freedom Now campaign. You can visit these sites to find out what net neutrality is (STI, NFN) and why it’s under threat (STI, NFN).
Briefly:

• Net neutrality is the principle that all bits are equal: that all users have equal access to the network, and service providers are not allowed to discriminate between users by means of different levels of service.
• It’s under threat because the greedy bastards in the cable/phone companies want to be able to decide which sites will load at what speed, so that they can privilege their own services and content and block their competitors’. Do you really want an internet on which you cannot send mail saying “AT&T sucks”? Don’t think it can’t happen. To make matters worse, those greedy bastards have bought some of these greedy bastards, and according to STI:
  

  Congress is now considering a major overhaul of the Telecommunications Act. The primary bill in the House is called the “Communications Opportunity, Promotion, and Enhancement Act of 2006”

  Unfortunately, I cannot find the text of this or any related bill on Thomas or by scanning House votes. If anyone can point me to the actual legislation in question I’d appreciate it. (I did manage to find S.2360, the Internet Non-Discrimination Act introduced by Ron Wyden and designed to protect net neutrality.)

• This matters to you because, to paraphrase David:
  • innovation and creativity: will suffer if your bank balance makes more difference than your brain power to what you can do on, and with, the web
  • monopoly: loss of net neutrality will create a breeding ground for anticompetitive practices; another Bell, anyone?
  • freedom of speech: this one ought to be self-explanatory
  • democracy: the web has been a great leveler of political playing fields (thank you, Dr Dean!) and promises to be a powerful way for ordinary people to have their voices heard — unless it becomes just another tool of the wealthy
• What you can do: for starters, send a letter to your Congresscritters here and sign MoveOn’s petition here. Include a note like mine:
  

  Keep the media conglomerates’ greedy hands off our internet! A neutral internet is a powerful engine of creativity, innovation, free speech, free markets and democracy. It must not be placed in the hands of a few wealthy campaign donors by greedy and short-sighted political opportunists. Please support Sen Wyden’s Internet Non-Discrimination Act (S.2360) and oppose the Barton/Rush COPE Act.