Okay, in general, good.

Now, for the social Internet, what are the purposes? E.g., why do 500+ million people use Facebook? Why do so many people use Twitter?

Okay, once we have thought about those old cases, assuming the huge amounts of data on social graphs in principle available, to what purpose might that data be put?

E.g., Fred Wilson wants to get copies of his social graphs and then manipulate, curate, them himself. Okay, but for what purposes?

Then as in the posts in his thread, how to process the social graph data automatically for Fred's or other purposes, and, again, what purposes?

E.g., maybe the purposes are introductions of one person to another or, say, one person to a group. Again, for what purposes? "May I have the envelope please?" Here is a list -- hobbies, careers, looking for a supplier, customer, employer, employee, date, spouse, cello in a string quartet.

Then if the purposes are mostly just introductions, how are the problem and solution much different than the introductions via the present romantic matchmaking sites?

Uh, Brin indicated that 99% of what can be done has yet to be done, or some such. So, what are the purposes of the other 99%? So, is Brin's 99% just an expansion of the idea of romantic matchmaking sites?

In simplest terms, what are the important candidate purposes for which people would want the results of software that manipulates data on social graphs?

I'm asking because the question seems big, hot, and important, and I don't have any very good answers. Here I may not be alone: Facebook, Twitter, etc. seem important, but finding clear and seemingly accurate statements of the important purposes they serve is not so easy.

But there is potentially a LOT of data so that if we could be clear on purposes, then maybe we could achieve some of them.

Let's do some guessing:

Social search might necessarily be quite close to personal interest search. Then the main purpose of social whatever on the Internet would be some personal interest so that doing a personal interest search would yield arcs in the user's social graph, where each such arc leads to a node good for that user's personal interest and, thus, leads to Wilson's "Building Better Social Graphs".

In particular, we can have bars, art galleries, concerts, adult education classes, country clubs, yacht clubs, high school and college alumni meetings, and, quite particular to the Internet, topical blogs.

So, each of these social activities can further a person's personal interests and build arcs in the person's corresponding social graph.

Then, perhaps, finding such a topical blog, the user could post some comments. Eventually maybe someone would post "For all blog users in and near Seattle, this Friday let's meet for pizza and beer at Joe's place".

So, the purpose would be to meet some people who share some interests and a geographical area.

The Internet has been used for such things. So, the purpose is to meet people with shared interests and geography. So, the purpose seems to be one that could be accomplished better by a slight generalization of Internet romantic matchmaking services.

If so, then how come Facebook and Twitter are big things far from the matchmaking services that are much smaller things?