Twitter co-founder Biz Stone has shared some insight into how Twitter selects accounts for the Suggested Users box. You know, that box that newcomers see when they sign up that Jason Calacanis is trying to buy a top spot in.

Stone makes it clear that Twitter does not sell these spots (at least not yet). We may very well change the way we populate this list or stop using it altogether if there is some other way to get the job done," he says.

But for now, Stone compares it to your local bookstore's "staff picks," though he acknowledges there's a little more to it than that. Stone explains:

Our Chief Scientist developed a program that scans active Twitter accounts for a bunch of key ingredients such as how much of the profile is filled out, certain indications that the account is interesting to others in some respects, and a few other signals.

This program then generates a list of potentially interesting Twitter accounts that myself and some product team folks here at Twitter take a look at for another set of criteria. For example, is the account a good introduction to Twittering for a new user? Does the person or organization running the account have a fairly wide or mainstream appeal?