What is Google's Lighthouse?

The Google Analyst Day earlier this week threw up a conspiracy theory of sorts, Is it a security function, or a next-generation search for desktop files? Or... with Google initially providing a powerpoint file of the presentation that had extensive notes about upcoming products named as: GDrive, GDS and Lighthouse. Greg Linden was one of the very few to download the powerpoint file, before it was mysteriously removed from Google's servers. Greg hadn't saved it, but Tomy Lorsch did actually save the 19 MB powerpoint file from Google onto his server. Tomy apparently downloaded it "right after Grek mentioned it in his blog", but alas it doesn't have any of the golden notes (I know, I downloaded it and checked).

So all we have to go on is what is in Greg's blog. One of his commenters copied and pasted the text about GDrive and Lighthouse from the retracted powerpoint:

"With infinite storage, we can house all user files, including: emails, web history, pictures, bookmarks, etc and make it accessible from anywhere (any device, any platform, etc).
We already have efforts in this direction in terms of GDrive, GDS, Lighthouse, but all of them face bandwidth and storage constraints today. For example: Firefox team is working on server side stored state but they want to store only URLs rather than complete web pages for storage reasons. This theme will help us make the client less important (thin client, thick server model) which suits our strength vis-a-vis Microsoft and is also of great value to the user.
As we move toward the "Store 100%" reality, the online copy of your data will become your Golden Copy and your local-machine copy serves more like a cache. An important implication of this theme is that we can make your online copy more secure than it would be on your own machine.
Another important implication of this theme is that storing 100% of a user's data makes each piece of data more valuable because it can be access across applications. For example: a user's Orkut profile has more value when it's accessible from Gmail (as addressbook), Lighthouse (as access list), etc."

Garett Rogers from ZDNet has already given a convincing explanation of what GDrive may be:

"The GDrive service will provide anyone (who trusts Google with their data) a universally accessible network share that spans across computers, operating systems and even devices."

GDS is probably Google Desktop Search - described on the Google Desktop site as:

"Search Across Computers enables you to search your documents and viewed web pages across all your computers."

So what is Lighthouse? Greg Linden asked this question, but didn't receive much enlightenment.

Here are my leading theories... From the powerpoint notes, we know that it's an access list of some sort. That seems to suggest Lighthouse is a security function that controls access to documents and folders - like an access control list. Or if you want a more poetic guess, Lighthouse could be a next-generation file search solution that 'shines a light' inside documents on your desktop. Thoughts?