From the YouTube Blog:

We think our users provide some of the most entertaining content in the world, and we're working to continuously develop new and exciting ways for you to broadcast yourself. What better way to do that than to give every user the ability to become their own channel? Now all content creators and collectors, be it professional filmmakers, videobloggers or just people who love chihuahuas can broadcast videos from their channel for all the world to see. You can visit our Channels tab to check out YouTube's most subscribed channels, or simply go to your profile to start creating and customizing your own channel. Here are just some of the new features included in channels:

• Color customization: make your channel look as cool or as ugly as you like.
• Video Log: showcase and discuss videos (yours or others) on your Channel
• Channels I'm watching: check out what channels other users are subscribed and find great new content

YouTube channeling its users - Yahoo! News