The decision to separate personal and professional identities online really comes down to how comfortable you are with your name in public. Advantages of separation include a layer of privacy that will remove your professional side from repercussions, and you have more control over who sees what. This extends to not bombarding friends and family with work-related updates that might otherwise bore them. The biggest disadvantage of separating your identities is doubling the amount of time it takes to maintain both networks. And if your professional career is dependent on an audience, then dividing your networks divides your audience. Consider using different networks for different purposes. You may not want a Facebook profile for professional networking, but a Facebook page might work perfectly for that.