[quote=Magic Magnum]Easier said than done. [/quote]
Nah. The only issue is presence. You act as a mediator; if conflict arises, you ask them to talk to you before they talk to each other. You gather their concerns, get a grip on the situation and base a decision off of it. Also explain your course of action. 

[quote=Magic Magnum]You're the story teller and/or organizer, but not the care taker. If your group of players are constantly bickering it's probably a sign your players just aren't a good mix.[/quote]
... No. Above all else, you're a facilitator. You provide the setting and plot for people to tell a story in. And I use storytelling loosely. However, besides the IC environment, you're also responsible for the OOC environment. If you allow shitstorms to rage on, you're doing a bad job as a GM. Take this from me; one shitstorm is enough to kill an entire game. But here's the thing. You don't give up, shrug and say "Well, I guess they just weren't a good mix." You make sure everyone sits down and talks it out. You create an environment where conflict is resolved. A lot of things can be resolved if you act quickly and properly, and your RP's will be healthier for it. Even if you lose a player or two in the process, simply creating that environment is an assurance to other players. People adapt to their environment, especially if they want to fit in, so make it a positive one.