How can I maximize the effectiveness of my professional online presence?

> Is a strong, unified online presence a requirement for freelance success?

No. Not in the least. I think a strong sense of marketing yourself is important, and that often ties into developing a strong online presence, but not a unified online presence.

> they have a professional identity that they use across communities, a blog full of relevant professional content, and an attitude towards community participation online pretty much opposite of my own.

That's only one way to do it. There are tons of successful freelancers / contractors that you haven't heard of (not because they aren't successful), but because they're working on developing their skills and getting work, not developing an online presence.

When you want to take the jump towards full time freelance work, I recommend Ramit Sethi's writings on earning more money (http://www.iwillteachyoutoberich.com/) or the earn1k program (http://www.earn1k.com).

IMO, you don't need to wait until you lose your job to start developing an online presence or to start freelancing.

I know that some online personalities have mentioned dual facebooks. [1]

Some people choose to go by a name that closely resembles their real name or in someway psuedo-anonymizes them. I think this works in some ways, but if anyone really wants to figure it out they can.

You don't need the same account name on Ebay and Amazon as you would have on twitter. That's a sort of middle ground.

It's important to figure out which is public facing and which is private facing. I'd use a version of noahc or mrnoahc for almost anything I want you to be able to find.

I can say that my hacker news comments have helped me a lot when reaching out to other people, and I suspect at a minimum you could at least point people to your comments on here.

http://www.chrisbrogan.com/families-run-on-facebook/

I understand your desire for privacy. And I think it's relatively achievable while maintaining an online presense. Of course the most successful individuals on the net you can point to as big personalities and identities. I do think to achieve that level of notoriety and influence, you need you have a very strong, and somewhat exposed online personality.

For just, what I'd call, regular online success, I don't think you need to be as exposed.

I've always been very aware of my online presence and exposure. I tend to be a private person, so I limit my exposure to my professional business. I don't talk about my personal life, and don't actually use facebook except for actual person connections. My twitter, on the other hand, is pretty much only about things that relate to my work life.