I think it would have a private part that enables you to manage connections to other homepages, control what's public and private, and aggregates news from other connections.
Well, if you look at it that way, a blog isn't any different than a traditional homepage either. :) But if not for the structure that blogs impose and the fact that non-technical people can edit them, the web would still be majority "Welcome to the Jones Family Homepage: Click to look at our vacation pictures from 2 years ago! (We can't update anymore because our kid moved out and we don't know how to change anything.)"
That aside, it looks like they're building in GPG based sharing (to limit _who_ you're actually sharing with—a more and more common problem these days) and some kind of capability to automatically publish to/subscribe from friends' nodes.
I think the main difference is that there would be a "behind the scenes" component that would allow profiles on different sites to exchange information in a secure way, while supporting different levels of privacy, etc.
I think a home page will play a part by integrating into the service. Instead of having a Facebook home page, you might go to any of a number of sites that would provide an aggregated view into your portion of the social fabric. Instead of looking at peoples profile pages, you would go to their profile page on a blog or anywhere else. This, too, would integrate into the underlying service.
