I think I've been in both camps at various points.
The sweet spot is when, like Hawk, work doesn't feel like work because you enjoy it.
It's like my job has become a training ground for my actual career which happens when I step out of the office. Is this how freelancing begins? Or is it a conscious choice? For me it seems to be evolving that way.
I think that for some people this is a natural evolution. If you're partial to educating, sharing, and reflecting, then blogging is the perfect medium for you to express that—and it also happens to be an activity that helps to build your personal brand, which then increases your exposure and authority in a niche, puts you out there, and increases the chance that random opportunities will come your way (like the Optimal Workshop thing for you).
So yes, blogging can open the doors to freelancing, a new job, or something crazy like the recent workshops that Luke and I taught in SE Asia (the UXMNL team in the Philippines followed our blog and emailed us to propose flying us over to teach the workshops—it was as simple as that).
Deciding to become a full-time freelancer needs to be a conscious decision though, because it requires planning before giving notice to your job. I say this speaking from experience, where I thought I was in a good position to begin freelancing (I was, but I wasn't well prepared for maintaining a freelance contract, and experienced some cashflow/tax hurdles that I could have avoided if I'd been better prepared). There is more to successful freelancing than being good at your chosen career, being well connected, and having an opportunity come along.
Luke and I are definitely happy to share our thoughts or answer questions on this topic if you like, Ashlea.