Net Neutrality is a sort of kept hush-hush thing on the Internet. But what Net Neutrality is is basically the Internet as you know and enjoy now. You have the freedom to access any information at any time using any service provider you choose and they have no right to block content. Of course, unlawful content like certain types of pornography and pirated software ("warez") are the only things that is actually regulated by governments, if they care to find it.
Why is this a big issue? Service providers want to sacrifice this freedom of information access for a "higher quality of service". They claim that bandwidth is wasted all the time on content they don't agree with. Basically they want to turn the Internet into cable TV. While the basic flat rate helps you keep in touch with most of the world, you still have to pay a premium for the extra content, like an HBO subscription or on-demand service. Also notice, just for the sake of example, that pornography that's all over the internet is nowhere to be found on cable TV.
So to prevent service providers from being controlling and effectively censoring the Internet, which we all know is supposed to be the free exchange of information, the FCC has set forth rules and regulations. You want this, because if say AT&T decides to cut off access to a website because they constantly crticize AT&T, well there's a problem there (but I guess not really advertising your competitors as much on cable is alright).
But basically it's the same shindig we've come to love for the past 15 or so years that Internet finally became mainstream. As long as the content is lawful, then it would be against FCC regulations to prohibit access to that content.
Which is kind of funny considering the FCC went on a censoring crusade after Janet Jacket's "wardobe slip" back in that Superbowl half-time show.
Sources: Maximum PC, FCC (PDF)