taken from http://www.zam.com/story.html?story=28045
ZAM Question #11: What are Free Companies, and how will these be structured? Are these the player-run companies we heard about in the past?

Yoshida: "These are player-controlled companies. You can think of it like the guild systems that a lot of other MMORPGs have, the player-run guilds. Think of it as each player, for example, five people can be a Free Company. I can be a member of the Order of the Twin Adder, he can be a member of the Maelstrom, he can be a member of the Immortal Flames, but we can all get together and make our own Free Company. Individuals can do the Grand Company content on their own, and then we can make this Free Company with a lot of people from different companies. And also, the Free Company can sign up to join the Grand Company, so you can experience Grand Company content through your Free Company, even though if I'm in Gridania but our Free Company signs up to work with the Maelstrom in Limsa Lominsa, then we can do those contents as well. That's one thing where players will be able to cross over.

"So when players make their own Free Companies, they can decide what they want to do. They can go, "OK, I only want to have people from the Order of the Twin Adder be in my Free Company, and their Free Company is going to be hardcore, or they can have a mixture of lots of different players. That will be up to the players."
Yoshida truly a win-win person