Isn't the concept of HOME simply a subset of multiplayer online game lobbies? There's nothing special about HOME imo.
If you're referring to the abstract concept of 3D world, then it's an old and nebulous idea (like parallelization in GPU).
In its full implementation scope, Home's uncertainty and design choices cover technology, business, social and legal issues.
Since it is positioned as a horizontal Virtual World platform (multi-developers instead of a vertical app like MMOG), it immediately reminds people of previous failed business attempts. Google Lively being the latest example. SecondLife is the most recently hyped (with low six digit subscribers ?). Mii and Avatar are really personalization subsystems. CyWorld succeeded in Korea but retreated from the US market. Beyond MMOGs, no one has truly succeeded in a big way (yet).
The value added services in Home (e.g., game spaces, club house, game launching, media sharing) are central to its experience. They layer on top of each other and pose combined usability, operational and marketing challenges. Sony partners may also toy with Home applications like Dress (e.g., selling apparels and other items for avatars and perhaps players at the same time).
It reminded me of similar social experiments to discover what will happen if users and avatars become one and the same (instead of the avatar being just a persona). However at this very moment, they have the opposite problem (Players are essentially anonymous). There are concerns whether gamers will troll Home to the extent that it become unusable. I believe Sony is learning how to manage the Home community as we speak.
Technologically speaking, Sony has to decide how open they want to make Home (e.g., user generated scripts, sharing objects between applications done by different developers). If the business model is unproven, Sony may also need to find cheap technical means to run and scale the platform (e.g., peer-to-peer 3D world). Security is another key concern if users are allowed to modify content in Home. For now, I believe they spent lotsa time developing tools for 3rd party developers to extend Home easily. These are not needed by a traditional MMOG.
Content-wise, some of these value added services like media sharing may introduce muddy copyright and censorship problems.
Overall, it's a can of worm. I believe when Home was announced, some MS exec (Shane Kim) thought it's an overly-ambitious project.
At the moment, it's a work-in-progress. ^_^
