Briefly, i-names are like DNS for people. They're based on open standards, and the core infrastructure will be open source. They are designed to support services that will allow individuals to control their digital identities, a vision largely inspired by the recent whitepaper, "The Augmented Social Network: Building Identity and Trust into the Next-Generation Internet."
Eugene Eric Kim has spoken at length about the Identity Commons and I-Names. The link under the title points to his post to the "yak" mailing list. I-Names form an important part of Augmented Social Networks, and, at the same time, they provide for subject identity for people who use them.