"Basically, we have been having conversations," Davidson tells DailyFinance. "We're in the very blue-sky, dreaming, 'If public radio were created today, what would it look like?' kind of phase."

In other words, everything's on the table -- including the possibility that whatever structure they come up with will involve a for-profit component in addition to the usual NPR combo of corporate underwriting and listener donations.

"Like everyone else in the business, we're trying to figure out if there are other revenue models that might work for us," says Davidson. "One of many possibilities raised has been the possibility, like many not-for-profits, of having a for-profit fundraising arm." But, he adds, "I can say with 100-percent assurance that our core goal is to be a not-for-profit, mission-driven company."

Another question that needs to be resolved is what, exactly, is the nature of Planet Money's relationships to NPR and to This American Life, which airs on NPR stations but is produced by Chicago Public Radio. Blumberg has said that he and Davidson have "something like ownership" of the brand, although what that means isn't quite clear. Part of the purpose of the discussions now underway is to codify that.

"The question is how can you be an entity that's sort of a partnership of two other entities, basically," says Davidson. "That's something the lawyers need to talk about."

But, he says, it's not a matter of Planet Money spinning off on its own; rather, he says, it's about "how to more formally recognize this rich and healthy partnership. We all want closer ties, and we're trying to figure out how to have closer ties."

Adds Davidson, "We started out in a very casual way, not knowing where things were going to go, and now it's like, 'Okay, we like each other. Maybe we should move in together and make a real commitment.'"