Three weeks ago Facebook Platform Manager Dave Morin announced he was leaving the company to start a stealthy new startup with Napster founder Sean Fanning.

The new company is called Path and you can sign up to request access to the closed beta at Path.io. Unfortunately, someone forgot to tell Google that the new company was in hiding and so tonight we have a fair amount of information about what these internet veterans are up to, courtesy of Google's cache of the otherwise locked-up site. The company describes itself as "a tool that facilitates the creation, sharing and correlation of lists." List creation is nothing new, but that's not a problem. When world-class social technologists tackle an age-old problem, the results can be quite interesting. Check out what this team has developed so far.

Morin and Fanning appear to be collaborating on the startup with Numair Faraz, an old friend of Napster, Plaxo and Facebook co-founder Sean Parker, and with some mysterious person named Fernando/L.C. from Portland, Oregon.

The site so far is a list of lists. You make a list, give it a name and add items to it. Then you can see who else has made a list with the same name, what's on their list and what the most popular items are across all lists with the same name. Lists are things like "best coffee in San Francisco," or "evil corporations." Faraz started a list with that title, but Facebook is the only company on it so far.

Much like Delicious, there's a nice clean URL structure like this: path.io/CharlesF/list/best_games or path.io/list/cute_videos or path.io/list/restaurants_in_sf/greens . The site appears aimed to have an API with advanced features like exposing geolocation, priorities and consensus.

It looks pretty basic so far, but there's a long list of beta users who have created lists titled "Features that Path needs to add." Some of those beta list builders are some very serious heavy-hitters, like Robert Kissinger (Director of Product Management & Interaction Designer at Electronic Arts), Joi Ito (CEO of Creative Commons) and Jordan Mendelson (Senior Product Manager, LinkedIn).

That Path team has put together a great list of beta testers, so when the company says it doesn't know yet what exactly it's going to launch, that has to be taken with a grain of salt.

Can a service for building lists really be that exciting? Many people asked the same question about a social Q&A site when another ex-Facebooker, Adam D'Angelo, recently launched Quora. (Which we also published the first screenshots of.) That site turned out to be amazing in terms of design and user experience.

We have high hopes for Path. It's another example of a basic human experience turned exciting by the network effects, location awareness, APIs and other features of the new social web. Just like Twitter and Facebook asked you what you were doing and made that the foundation for a world-changing technology platform, now services like Foursquare and Gowalla are trying to do the same with where you are, Plancast with what you're planning on doing in the future and, we suspect, Path with what you like to bundle together in a list. We look forward to seeing what this All-Star team puts together.

We don't know yet when Path will launch. We'll update this post with more information from the founders as we receive it and we'll take a much closer look once we get access to the site itself.